<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019c5355-1df1-7cfa-b583-0602b2d1b382,g:73b6b095-4ae8-4954-be2f-5e3653a654d0-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="moh-20260331.xsd#CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019c5355-1f66-7ff0-807d-762b3ade5a20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019c5355-1f66-706f-a7ca-d92a673b0b3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019c5355-1f66-7ff0-807d-762b3ade5a20" xlink:to="loc_us-gaap_StatementTable_019c5355-1f66-706f-a7ca-d92a673b0b3f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019c5355-1f66-7041-bee7-069a8030ba77" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019c5355-1f66-706f-a7ca-d92a673b0b3f" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019c5355-1f66-7041-bee7-069a8030ba77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019c5355-1f66-7041-bee7-069a8030ba77_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019c5355-1f66-7041-bee7-069a8030ba77" xlink:to="loc_us-gaap_EquityComponentDomain_019c5355-1f66-7041-bee7-069a8030ba77_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019c5355-1f66-7dbf-ab79-5f387c9a70a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019c5355-1f66-7041-bee7-069a8030ba77" xlink:to="loc_us-gaap_EquityComponentDomain_019c5355-1f66-7dbf-ab79-5f387c9a70a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019c5355-1f66-7772-81e9-374f4806b548" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019c5355-1f66-7dbf-ab79-5f387c9a70a9" xlink:to="loc_us-gaap_CommonStockMember_019c5355-1f66-7772-81e9-374f4806b548" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019c5355-1f66-75a1-952a-83fabee93ac9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019c5355-1f66-7dbf-ab79-5f387c9a70a9" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019c5355-1f66-75a1-952a-83fabee93ac9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019c5355-1f66-7eb1-8420-1436f3443ca1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019c5355-1f66-7dbf-ab79-5f387c9a70a9" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019c5355-1f66-7eb1-8420-1436f3443ca1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019c5355-1f66-7d4a-838a-ff73f05de2e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019c5355-1f66-7dbf-ab79-5f387c9a70a9" xlink:to="loc_us-gaap_RetainedEarningsMember_019c5355-1f66-7d4a-838a-ff73f05de2e1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019c5355-1f66-7ff0-807d-762b3ade5a20" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019c5355-1f66-7fc0-a7c2-dc61af801557" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019c5355-1f66-7fc0-a7c2-dc61af801557" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019c5355-1f66-7c3e-bef1-4ad8196bd1bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_StockholdersEquity_019c5355-1f66-7c3e-bef1-4ad8196bd1bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019c5355-1f66-73e0-b018-3d3368a61f5f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_NetIncomeLoss_019c5355-1f66-73e0-b018-3d3368a61f5f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019c5355-1f66-7ddd-9932-143d09c83df6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019c5355-1f66-7ddd-9932-143d09c83df6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019c5355-1f66-76b4-a723-66647afa00c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019c5355-1f66-76b4-a723-66647afa00c4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramExciseTax_019c5355-1f66-7ceb-995f-99c7234d2615" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareRepurchaseProgramExciseTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_ShareRepurchaseProgramExciseTax_019c5355-1f66-7ceb-995f-99c7234d2615" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019c5355-1f66-7937-97f8-2269e6df6266" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019c5355-1f66-7937-97f8-2269e6df6266" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019c5355-1f66-7f4d-bf5b-d8477be479eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019c5355-1f66-7f4d-bf5b-d8477be479eb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019c5355-1f66-753d-b937-ebbb4d45c9aa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019c5355-1f66-7925-b20b-974b7241263e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019c5355-1f66-753d-b937-ebbb4d45c9aa" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019c5355-1f66-7f95-b83e-cdd18aef2b9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019c5355-1f66-7fe9-bdcc-e1444a15a0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/OrganizationandBasisofPresentationDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#OrganizationandBasisofPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/OrganizationandBasisofPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_moh_BasisOfPresentationLineItems_019c5355-1f66-73e8-b5b9-602a246f060d" xlink:href="moh-20260331.xsd#moh_BasisOfPresentationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_BasisOfPresentationTable_019c5355-1f66-7041-a635-ecd6d99d8c01" xlink:href="moh-20260331.xsd#moh_BasisOfPresentationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_moh_BasisOfPresentationLineItems_019c5355-1f66-73e8-b5b9-602a246f060d" xlink:to="loc_moh_BasisOfPresentationTable_019c5355-1f66-7041-a635-ecd6d99d8c01" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-1f66-7072-a64e-8a59e44ee7aa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_moh_BasisOfPresentationTable_019c5355-1f66-7041-a635-ecd6d99d8c01" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-1f66-7072-a64e-8a59e44ee7aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019c5355-1f66-7072-a64e-8a59e44ee7aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-1f66-7072-a64e-8a59e44ee7aa" xlink:to="loc_us-gaap_SegmentDomain_019c5355-1f66-7072-a64e-8a59e44ee7aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019c5355-1f66-72fa-9fef-f1f12bdb14ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-1f66-7072-a64e-8a59e44ee7aa" xlink:to="loc_us-gaap_SegmentDomain_019c5355-1f66-72fa-9fef-f1f12bdb14ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_HealthPlansMember_019c5355-1f66-7721-9b85-edd07c06651f" xlink:href="moh-20260331.xsd#moh_HealthPlansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-1f66-72fa-9fef-f1f12bdb14ff" xlink:to="loc_moh_HealthPlansMember_019c5355-1f66-7721-9b85-edd07c06651f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicaidMember_019c5355-1f66-74a8-bac5-ad9ea9615b8a" xlink:href="moh-20260331.xsd#moh_MedicaidMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-1f66-72fa-9fef-f1f12bdb14ff" xlink:to="loc_moh_MedicaidMember_019c5355-1f66-74a8-bac5-ad9ea9615b8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicareMember_019c5355-1f66-7ff6-8b60-02542bc18d62" xlink:href="moh-20260331.xsd#moh_MedicareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-1f66-72fa-9fef-f1f12bdb14ff" xlink:to="loc_moh_MedicareMember_019c5355-1f66-7ff6-8b60-02542bc18d62" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019c5355-1f66-770b-b34f-1e0f33f1bdb7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_moh_BasisOfPresentationTable_019c5355-1f66-7041-a635-ecd6d99d8c01" xlink:to="loc_srt_RangeAxis_019c5355-1f66-770b-b34f-1e0f33f1bdb7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019c5355-1f66-770b-b34f-1e0f33f1bdb7_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019c5355-1f66-770b-b34f-1e0f33f1bdb7" xlink:to="loc_srt_RangeMember_019c5355-1f66-770b-b34f-1e0f33f1bdb7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019c5355-1f66-78e4-8d3b-4102bb5cd6c8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019c5355-1f66-770b-b34f-1e0f33f1bdb7" xlink:to="loc_srt_RangeMember_019c5355-1f66-78e4-8d3b-4102bb5cd6c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019c5355-1f66-7359-b55a-89bf4f470b11" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019c5355-1f66-78e4-8d3b-4102bb5cd6c8" xlink:to="loc_srt_MinimumMember_019c5355-1f66-7359-b55a-89bf4f470b11" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019c5355-1f66-74af-8b4f-62956a9202a6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019c5355-1f66-78e4-8d3b-4102bb5cd6c8" xlink:to="loc_srt_MaximumMember_019c5355-1f66-74af-8b4f-62956a9202a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019c5355-1f66-7f83-bc30-2f02fd4dbf0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_BasisOfPresentationLineItems_019c5355-1f66-73e8-b5b9-602a246f060d" xlink:to="loc_us-gaap_NumberOfReportableSegments_019c5355-1f66-7f83-bc30-2f02fd4dbf0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_NumberOfMembersEligibleForGovernmentSponsoredHealthcarePrograms_019c5355-1f66-79c3-9cae-f81b9ab45cc8" xlink:href="moh-20260331.xsd#moh_NumberOfMembersEligibleForGovernmentSponsoredHealthcarePrograms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_BasisOfPresentationLineItems_019c5355-1f66-73e8-b5b9-602a246f060d" xlink:to="loc_moh_NumberOfMembersEligibleForGovernmentSponsoredHealthcarePrograms_019c5355-1f66-79c3-9cae-f81b9ab45cc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_NumberOfStatesWithGovernmentSponsoredHealthcarePrograms_019c5355-1f66-75fe-9707-adf8f52a4fce" xlink:href="moh-20260331.xsd#moh_NumberOfStatesWithGovernmentSponsoredHealthcarePrograms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_BasisOfPresentationLineItems_019c5355-1f66-73e8-b5b9-602a246f060d" xlink:to="loc_moh_NumberOfStatesWithGovernmentSponsoredHealthcarePrograms_019c5355-1f66-75fe-9707-adf8f52a4fce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_HealthPlanContractTerm_019c5355-1f66-7d03-aab5-c68ab6e34c3b" xlink:href="moh-20260331.xsd#moh_HealthPlanContractTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_BasisOfPresentationLineItems_019c5355-1f66-73e8-b5b9-602a246f060d" xlink:to="loc_moh_HealthPlanContractTerm_019c5355-1f66-7d03-aab5-c68ab6e34c3b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/SignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#SignificantAccountingPoliciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/SignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019c5355-1f66-70cd-b586-58226e58ff20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019c5355-1f66-70cd-b586-58226e58ff20" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_019c5355-1f66-7820-b865-f696214a5df5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019c5355-1f66-70cd-b586-58226e58ff20" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_019c5355-1f66-7820-b865-f696214a5df5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_019c5355-1f66-7820-b865-f696214a5df5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_019c5355-1f66-7820-b865-f696214a5df5" xlink:to="loc_us-gaap_ReceivableTypeDomain_019c5355-1f66-7820-b865-f696214a5df5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_019c5355-1f66-7b33-b518-5d4cf61efb19" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_019c5355-1f66-7820-b865-f696214a5df5" xlink:to="loc_us-gaap_ReceivableTypeDomain_019c5355-1f66-7b33-b518-5d4cf61efb19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_GovernmentReceivablesMember_019c5355-1f66-7cf3-8faf-7095224f9e93" xlink:href="moh-20260331.xsd#moh_GovernmentReceivablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_019c5355-1f66-7b33-b518-5d4cf61efb19" xlink:to="loc_moh_GovernmentReceivablesMember_019c5355-1f66-7cf3-8faf-7095224f9e93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7b74-b0aa-225d0c8b7bec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019c5355-1f66-70cd-b586-58226e58ff20" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7b74-b0aa-225d0c8b7bec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7b74-b0aa-225d0c8b7bec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7b74-b0aa-225d0c8b7bec" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7b74-b0aa-225d0c8b7bec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-778a-8856-2794b3e5fdaf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7b74-b0aa-225d0c8b7bec" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-778a-8856-2794b3e5fdaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_StructuredSecuritiesMember_019c5355-1f66-72ee-aa40-90ef352fa360" xlink:href="moh-20260331.xsd#moh_StructuredSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-778a-8856-2794b3e5fdaf" xlink:to="loc_moh_StructuredSecuritiesMember_019c5355-1f66-72ee-aa40-90ef352fa360" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019d5138-2738-71a4-bebe-de9ebefda9a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019c5355-1f66-70cd-b586-58226e58ff20" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019d5138-2738-71a4-bebe-de9ebefda9a7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019d5138-2738-71a4-bebe-de9ebefda9a7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019d5138-2738-71a4-bebe-de9ebefda9a7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019d5138-2738-71a4-bebe-de9ebefda9a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019d5138-2738-71ec-8720-33b72279b984" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019d5138-2738-71a4-bebe-de9ebefda9a7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019d5138-2738-71ec-8720-33b72279b984" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_ContractRightsAndLicensesMember_019d5138-2738-776d-ae0e-1d4e57535515" xlink:href="moh-20260331.xsd#moh_ContractRightsAndLicensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019d5138-2738-71ec-8720-33b72279b984" xlink:to="loc_moh_ContractRightsAndLicensesMember_019d5138-2738-776d-ae0e-1d4e57535515" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_ProviderNetworksMember_019d5138-2738-7042-a5df-6a2d5b0637dd" xlink:href="moh-20260331.xsd#moh_ProviderNetworksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019d5138-2738-71ec-8720-33b72279b984" xlink:to="loc_moh_ProviderNetworksMember_019d5138-2738-7042-a5df-6a2d5b0637dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_019d5138-2738-7175-b3b7-d6c5e8f8d1c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019d5138-2738-71ec-8720-33b72279b984" xlink:to="loc_us-gaap_TradeNamesMember_019d5138-2738-7175-b3b7-d6c5e8f8d1c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesNetCurrent_019c5355-1f66-71a6-97f9-581b0be2d5cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReceivablesNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_us-gaap_ReceivablesNetCurrent_019c5355-1f66-71a6-97f9-581b0be2d5cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicalPremiumsLiabilityMedicalCareCostsThreshold_019c5355-1f66-7961-8634-21843b65403f" xlink:href="moh-20260331.xsd#moh_MedicalPremiumsLiabilityMedicalCareCostsThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_MedicalPremiumsLiabilityMedicalCareCostsThreshold_019c5355-1f66-7961-8634-21843b65403f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold_019c5355-1f66-7631-9e87-c93dba738e9c" xlink:href="moh-20260331.xsd#moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold_019c5355-1f66-7631-9e87-c93dba738e9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AmountsDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold_019c5355-1f66-7671-86ec-0a18677c0cc5" xlink:href="moh-20260331.xsd#moh_AmountsDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_AmountsDueToGovernmentAgenciesMedicareMedicalLossRatioAndProfitSharingThreshold_019c5355-1f66-7671-86ec-0a18677c0cc5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace_019c5355-1f66-7bf5-b337-ef028582219b" xlink:href="moh-20260331.xsd#moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_PercentDueToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace_019c5355-1f66-7bf5-b337-ef028582219b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AmountToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace_019c5355-1f66-7c91-b7d2-c7eb18b366aa" xlink:href="moh-20260331.xsd#moh_AmountToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_AmountToGovernmentAgenciesMedicareMedicalLossRatioOfMarketplace_019c5355-1f66-7c91-b7d2-c7eb18b366aa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AmountsDueToGovernmentAgenciesRiskAdjustmentAndPartDRiskSharing_019c5355-1f66-74ab-b750-aba18ed9e1d6" xlink:href="moh-20260331.xsd#moh_AmountsDueToGovernmentAgenciesRiskAdjustmentAndPartDRiskSharing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_AmountsDueToGovernmentAgenciesRiskAdjustmentAndPartDRiskSharing_019c5355-1f66-74ab-b750-aba18ed9e1d6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentPayable_019c5355-1f66-7f38-b943-52c0d0ba70da" xlink:href="moh-20260331.xsd#moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentPayable_019c5355-1f66-7f38-b943-52c0d0ba70da" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentReceivable_019c5355-1f66-78e6-9bb0-590783a6d2d3" xlink:href="moh-20260331.xsd#moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentReceivable_019c5355-1f66-78e6-9bb0-590783a6d2d3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentNetReceivable_019c5355-1f66-79de-a623-f0ee90f0d330" xlink:href="moh-20260331.xsd#moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentNetReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentNetReceivable_019c5355-1f66-79de-a623-f0ee90f0d330" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_InvestmentsMaturityPeriod_019c5355-1f66-75c1-b309-16a7d20b85d9" xlink:href="moh-20260331.xsd#moh_InvestmentsMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_InvestmentsMaturityPeriod_019c5355-1f66-75c1-b309-16a7d20b85d9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_InvestmentsAverageMaturityPeriod_019c5355-1f66-75a3-b8c0-ce08f6d78d3b" xlink:href="moh-20260331.xsd#moh_InvestmentsAverageMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_moh_InvestmentsAverageMaturityPeriod_019c5355-1f66-75a3-b8c0-ce08f6d78d3b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_019d74f3-126f-7ca7-b644-6fba56501e2c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019c5355-1f66-7dc3-9e1a-6e069626779b" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_019d74f3-126f-7ca7-b644-6fba56501e2c" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/FairValueMeasurementsFinancialInstrumentsonaRecurringBasisDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#FairValueMeasurementsFinancialInstrumentsonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/FairValueMeasurementsFinancialInstrumentsonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019c5355-1f66-7085-aead-a61288eddf05" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019c5355-1f66-71f1-a00f-7bd649afae25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019c5355-1f66-7085-aead-a61288eddf05" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019c5355-1f66-71f1-a00f-7bd649afae25" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019c5355-1f66-7995-8df8-9ee70ef4d6e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019c5355-1f66-71f1-a00f-7bd649afae25" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019c5355-1f66-7995-8df8-9ee70ef4d6e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019c5355-1f66-7995-8df8-9ee70ef4d6e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019c5355-1f66-7995-8df8-9ee70ef4d6e4" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019c5355-1f66-7995-8df8-9ee70ef4d6e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019c5355-1f66-777c-9203-228f8c02746c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019c5355-1f66-7995-8df8-9ee70ef4d6e4" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019c5355-1f66-777c-9203-228f8c02746c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019c5355-1f66-7fef-9d58-593e865be05b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019c5355-1f66-777c-9203-228f8c02746c" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019c5355-1f66-7fef-9d58-593e865be05b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019c5355-1f66-7bc7-a59d-0af66954f06b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019c5355-1f66-777c-9203-228f8c02746c" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019c5355-1f66-7bc7-a59d-0af66954f06b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019c5355-1f66-7648-a40d-157cc636b5db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019c5355-1f66-777c-9203-228f8c02746c" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019c5355-1f66-7648-a40d-157cc636b5db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7971-af2e-174572734056" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019c5355-1f66-71f1-a00f-7bd649afae25" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7971-af2e-174572734056" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7971-af2e-174572734056_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7971-af2e-174572734056" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7971-af2e-174572734056_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7402-baee-1ec9572afe20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7971-af2e-174572734056" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7402-baee-1ec9572afe20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019c5355-1f66-7856-b0a8-0c79502e33a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7402-baee-1ec9572afe20" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019c5355-1f66-7856-b0a8-0c79502e33a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_019c5355-1f66-773b-b968-78860f717624" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7402-baee-1ec9572afe20" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_019c5355-1f66-773b-b968-78860f717624" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019c5355-1f66-7448-bb4b-68feaa5a8c0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7402-baee-1ec9572afe20" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019c5355-1f66-7448-bb4b-68feaa5a8c0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MunicipalSecuritiesMember_019c5355-1f66-72b6-b3f7-16b5d84f6449" xlink:href="moh-20260331.xsd#moh_MunicipalSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7402-baee-1ec9572afe20" xlink:to="loc_moh_MunicipalSecuritiesMember_019c5355-1f66-72b6-b3f7-16b5d84f6449" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryNotesSecuritiesMember_019c5355-1f66-7cc6-9316-e2e125929df4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryNotesSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7402-baee-1ec9572afe20" xlink:to="loc_us-gaap_USTreasuryNotesSecuritiesMember_019c5355-1f66-7cc6-9316-e2e125929df4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherSecuritiesMember_019c5355-1f66-7aed-9fcf-7b15c4c46293" xlink:href="moh-20260331.xsd#moh_OtherSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7402-baee-1ec9572afe20" xlink:to="loc_moh_OtherSecuritiesMember_019c5355-1f66-7aed-9fcf-7b15c4c46293" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_019c5355-1f66-74fb-a459-17d446b6703a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019c5355-1f66-7085-aead-a61288eddf05" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_019c5355-1f66-74fb-a459-17d446b6703a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019c5355-1f66-71cf-8977-b9aa8b926e74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019c5355-1f66-74fb-a459-17d446b6703a" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019c5355-1f66-71cf-8977-b9aa8b926e74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019c5355-1f66-7414-a25e-c0ca8dba1e0b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019c5355-1f66-74fb-a459-17d446b6703a" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019c5355-1f66-7414-a25e-c0ca8dba1e0b" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/FairValueMeasurementsLongTermDebtDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#FairValueMeasurementsLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/FairValueMeasurementsLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019c5355-1f66-7d55-a077-2d564c53599a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019c5355-1f66-7a3b-9851-5e998e6ee4c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019c5355-1f66-7d55-a077-2d564c53599a" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019c5355-1f66-7a3b-9851-5e998e6ee4c6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019c5355-1f66-7ab6-8c92-a57bf3b45ff7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019c5355-1f66-7a3b-9851-5e998e6ee4c6" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019c5355-1f66-7ab6-8c92-a57bf3b45ff7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019c5355-1f66-7ab6-8c92-a57bf3b45ff7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019c5355-1f66-7ab6-8c92-a57bf3b45ff7" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019c5355-1f66-7ab6-8c92-a57bf3b45ff7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019c5355-1f66-7147-80b3-2d1dffe390bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019c5355-1f66-7ab6-8c92-a57bf3b45ff7" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019c5355-1f66-7147-80b3-2d1dffe390bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019c5355-1f66-73f1-a18a-1aac584c3889" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019c5355-1f66-7147-80b3-2d1dffe390bf" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019c5355-1f66-73f1-a18a-1aac584c3889" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019c5355-1f66-746e-9848-cae8091490fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019c5355-1f66-73f1-a18a-1aac584c3889" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019c5355-1f66-746e-9848-cae8091490fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019c5355-1f66-7004-b6a2-ee3894ac52fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019c5355-1f66-73f1-a18a-1aac584c3889" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019c5355-1f66-7004-b6a2-ee3894ac52fa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019c5355-1f66-7b2f-8cbd-6fd101f1faa2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019c5355-1f66-7a3b-9851-5e998e6ee4c6" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019c5355-1f66-7b2f-8cbd-6fd101f1faa2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019c5355-1f66-7b2f-8cbd-6fd101f1faa2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019c5355-1f66-7b2f-8cbd-6fd101f1faa2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019c5355-1f66-7b2f-8cbd-6fd101f1faa2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019c5355-1f66-7a7d-b17e-d809c188c8fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019c5355-1f66-7b2f-8cbd-6fd101f1faa2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019c5355-1f66-7a7d-b17e-d809c188c8fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019c5355-1f66-7e70-9eaf-418206e850eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019c5355-1f66-7a7d-b17e-d809c188c8fc" xlink:to="loc_us-gaap_SeniorNotesMember_019c5355-1f66-7e70-9eaf-418206e850eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019c5355-1f66-7872-83c9-d2c7cbaa76b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019c5355-1f66-7a3b-9851-5e998e6ee4c6" xlink:to="loc_us-gaap_DebtInstrumentAxis_019c5355-1f66-7872-83c9-d2c7cbaa76b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7872-83c9-d2c7cbaa76b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019c5355-1f66-7872-83c9-d2c7cbaa76b8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7872-83c9-d2c7cbaa76b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7c97-b08d-c7fce2929bde" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019c5355-1f66-7872-83c9-d2c7cbaa76b8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7c97-b08d-c7fce2929bde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A4.375SeniorNotesDue2028Member_019c5355-1f66-730a-a88b-21457fbec5e5" xlink:href="moh-20260331.xsd#moh_A4.375SeniorNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7c97-b08d-c7fce2929bde" xlink:to="loc_moh_A4.375SeniorNotesDue2028Member_019c5355-1f66-730a-a88b-21457fbec5e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A3.875SeniorNotesDue2030Member_019c5355-1f66-7329-bb28-c7e2748bdea9" xlink:href="moh-20260331.xsd#moh_A3.875SeniorNotesDue2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7c97-b08d-c7fce2929bde" xlink:to="loc_moh_A3.875SeniorNotesDue2030Member_019c5355-1f66-7329-bb28-c7e2748bdea9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A6.500SeniorNotesDue2031Member_019cdd9e-9031-78b8-b7a3-fc26821e5baf" xlink:href="moh-20260331.xsd#moh_A6.500SeniorNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7c97-b08d-c7fce2929bde" xlink:to="loc_moh_A6.500SeniorNotesDue2031Member_019cdd9e-9031-78b8-b7a3-fc26821e5baf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A3.875SeniorNotesDue2032Member_019c5355-1f66-77bc-8b41-d4323387dff3" xlink:href="moh-20260331.xsd#moh_A3.875SeniorNotesDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7c97-b08d-c7fce2929bde" xlink:to="loc_moh_A3.875SeniorNotesDue2032Member_019c5355-1f66-77bc-8b41-d4323387dff3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A6.250SeniorNotesDue2033Member_019c5355-1f66-7d1e-8972-4678d236b513" xlink:href="moh-20260331.xsd#moh_A6.250SeniorNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-1f66-7c97-b08d-c7fce2929bde" xlink:to="loc_moh_A6.250SeniorNotesDue2033Member_019c5355-1f66-7d1e-8972-4678d236b513" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019c5355-1f66-7ad2-be73-5e6e7f282484" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019c5355-1f66-7d55-a077-2d564c53599a" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019c5355-1f66-7ad2-be73-5e6e7f282484" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_019c5355-1f66-75c6-868e-daa85ddaf7a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019c5355-1f66-7d55-a077-2d564c53599a" xlink:to="loc_us-gaap_DebtInstrumentFairValue_019c5355-1f66-75c6-868e-daa85ddaf7a1" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/InvestmentsScheduleofInvestmentsDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#InvestmentsScheduleofInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/InvestmentsScheduleofInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7dd7-a709-0ab6ab6ace7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019c5355-1f66-7194-9e2a-c741b0986f3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7dd7-a709-0ab6ab6ace7f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019c5355-1f66-7194-9e2a-c741b0986f3d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7947-ac46-23e8ada76bba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019c5355-1f66-7194-9e2a-c741b0986f3d" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7947-ac46-23e8ada76bba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7947-ac46-23e8ada76bba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7947-ac46-23e8ada76bba" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7947-ac46-23e8ada76bba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7fd2-92d9-6ca83b8c4d3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7947-ac46-23e8ada76bba" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7fd2-92d9-6ca83b8c4d3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019c5355-1f66-765a-a605-942d575be26d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7fd2-92d9-6ca83b8c4d3a" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019c5355-1f66-765a-a605-942d575be26d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesMember_019c5355-1f66-7547-9c61-f83fe44815ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7fd2-92d9-6ca83b8c4d3a" xlink:to="loc_us-gaap_MortgageBackedSecuritiesMember_019c5355-1f66-7547-9c61-f83fe44815ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019c5355-1f66-772e-aec1-d9e7358438f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7fd2-92d9-6ca83b8c4d3a" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019c5355-1f66-772e-aec1-d9e7358438f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MunicipalSecuritiesMember_019c5355-1f66-7bfe-aa50-c03372981ba7" xlink:href="moh-20260331.xsd#moh_MunicipalSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7fd2-92d9-6ca83b8c4d3a" xlink:to="loc_moh_MunicipalSecuritiesMember_019c5355-1f66-7bfe-aa50-c03372981ba7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryNotesSecuritiesMember_019c5355-1f66-706d-9ae5-7ea37bd04f02" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasuryNotesSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7fd2-92d9-6ca83b8c4d3a" xlink:to="loc_us-gaap_USTreasuryNotesSecuritiesMember_019c5355-1f66-706d-9ae5-7ea37bd04f02" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherSecuritiesMember_019c5355-1f66-7dfa-9e45-d04472191eae" xlink:href="moh-20260331.xsd#moh_OtherSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7fd2-92d9-6ca83b8c4d3a" xlink:to="loc_moh_OtherSecuritiesMember_019c5355-1f66-7dfa-9e45-d04472191eae" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_019c5355-1f66-76dc-b2aa-b3c94d57245d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7dd7-a709-0ab6ab6ace7f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_019c5355-1f66-76dc-b2aa-b3c94d57245d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019c5355-1f66-7f85-b1a2-b0a9d9c8b607" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7dd7-a709-0ab6ab6ace7f" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019c5355-1f66-7f85-b1a2-b0a9d9c8b607" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019c5355-1f66-78bc-a41c-b823b1011c12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7dd7-a709-0ab6ab6ace7f" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019c5355-1f66-78bc-a41c-b823b1011c12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019c5355-1f66-755d-911e-c8012f832663" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7dd7-a709-0ab6ab6ace7f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_019c5355-1f66-755d-911e-c8012f832663" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/InvestmentsAvailableforSaleInvestmentsDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#InvestmentsAvailableforSaleInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/InvestmentsAvailableforSaleInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7caf-bdfb-364e39546d99" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019c5355-1f66-79c8-99cf-6be6e18c282b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7caf-bdfb-364e39546d99" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019c5355-1f66-79c8-99cf-6be6e18c282b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7090-b0e6-325f2c3c7f1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_019c5355-1f66-79c8-99cf-6be6e18c282b" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7090-b0e6-325f2c3c7f1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7090-b0e6-325f2c3c7f1d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7090-b0e6-325f2c3c7f1d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7090-b0e6-325f2c3c7f1d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7984-a0f7-cb17c206b9ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019c5355-1f66-7090-b0e6-325f2c3c7f1d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7984-a0f7-cb17c206b9ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019c5355-1f66-7049-b6aa-7d26c2e84bfc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7984-a0f7-cb17c206b9ed" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019c5355-1f66-7049-b6aa-7d26c2e84bfc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesMember_019c5355-1f66-7b02-9c17-556174a9f79f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7984-a0f7-cb17c206b9ed" xlink:to="loc_us-gaap_MortgageBackedSecuritiesMember_019c5355-1f66-7b02-9c17-556174a9f79f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019c5355-1f66-74ba-bc87-a41b2bc42090" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7984-a0f7-cb17c206b9ed" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019c5355-1f66-74ba-bc87-a41b2bc42090" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MunicipalSecuritiesMember_019c5355-1f66-7a20-9111-88922c785e2f" xlink:href="moh-20260331.xsd#moh_MunicipalSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7984-a0f7-cb17c206b9ed" xlink:to="loc_moh_MunicipalSecuritiesMember_019c5355-1f66-7a20-9111-88922c785e2f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherSecuritiesMember_019c5355-1f66-70fa-b529-3cc37f13d454" xlink:href="moh-20260331.xsd#moh_OtherSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019c5355-1f66-7984-a0f7-cb17c206b9ed" xlink:to="loc_moh_OtherSecuritiesMember_019c5355-1f66-70fa-b529-3cc37f13d454" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_019c5355-1f66-7cfc-a1af-b2fc38042ec3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7caf-bdfb-364e39546d99" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_019c5355-1f66-7cfc-a1af-b2fc38042ec3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_019c5355-1f66-7782-81a1-1099d182c38e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7caf-bdfb-364e39546d99" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_019c5355-1f66-7782-81a1-1099d182c38e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_019c5355-1f66-7c08-b2e5-916ece573a48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7caf-bdfb-364e39546d99" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_019c5355-1f66-7c08-b2e5-916ece573a48" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019c5355-1f66-7ac9-9e3b-dfed822a79d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7caf-bdfb-364e39546d99" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019c5355-1f66-7ac9-9e3b-dfed822a79d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_019c5355-1f66-7dd2-bb71-c4a12fa502ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7caf-bdfb-364e39546d99" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_019c5355-1f66-7dd2-bb71-c4a12fa502ee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_019c5355-1f66-799e-864c-fa705da7d845" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_019c5355-1f66-7caf-bdfb-364e39546d99" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_019c5355-1f66-799e-864c-fa705da7d845" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/MedicalClaimsandBenefitsPayableComponentsofChangeinMedicalClaimsandBenefitsPayableDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#MedicalClaimsandBenefitsPayableComponentsofChangeinMedicalClaimsandBenefitsPayableDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/MedicalClaimsandBenefitsPayableComponentsofChangeinMedicalClaimsandBenefitsPayableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_019c5355-1f66-7c20-ad6e-b0db9b7f72c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_019c5355-1f66-7442-a354-e8d02539021f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_019c5355-1f66-7c20-ad6e-b0db9b7f72c7" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_019c5355-1f66-7442-a354-e8d02539021f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-1f66-7bcf-b899-d44ef96db85d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_019c5355-1f66-7442-a354-e8d02539021f" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-1f66-7bcf-b899-d44ef96db85d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019c5355-1f66-7bcf-b899-d44ef96db85d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-1f66-7bcf-b899-d44ef96db85d" xlink:to="loc_us-gaap_SegmentDomain_019c5355-1f66-7bcf-b899-d44ef96db85d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019c5355-1f66-7840-9ada-7f052d7526c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-1f66-7bcf-b899-d44ef96db85d" xlink:to="loc_us-gaap_SegmentDomain_019c5355-1f66-7840-9ada-7f052d7526c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicaidMember_019c5355-1f66-7923-b1c0-8b40c7276498" xlink:href="moh-20260331.xsd#moh_MedicaidMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-1f66-7840-9ada-7f052d7526c8" xlink:to="loc_moh_MedicaidMember_019c5355-1f66-7923-b1c0-8b40c7276498" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicareMember_019c5355-1f66-72b9-92da-5a02e56e9158" xlink:href="moh-20260331.xsd#moh_MedicareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-1f66-7840-9ada-7f052d7526c8" xlink:to="loc_moh_MedicareMember_019c5355-1f66-72b9-92da-5a02e56e9158" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MarketplaceMember_019c5355-1f66-7bd3-a67a-a729f74e5268" xlink:href="moh-20260331.xsd#moh_MarketplaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-1f66-7840-9ada-7f052d7526c8" xlink:to="loc_moh_MarketplaceMember_019c5355-1f66-7bd3-a67a-a729f74e5268" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherProgramMember_019c5355-1f66-7a66-a680-7ca283e4d9e5" xlink:href="moh-20260331.xsd#moh_OtherProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-1f66-7840-9ada-7f052d7526c8" xlink:to="loc_moh_OtherProgramMember_019c5355-1f66-7a66-a680-7ca283e4d9e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019c5355-1f66-7471-8903-92be8c7fc8f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_019c5355-1f66-7c20-ad6e-b0db9b7f72c7" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019c5355-1f66-7471-8903-92be8c7fc8f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019c5355-1f66-7c36-a7ed-bcd1eceb58f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019c5355-1f66-7471-8903-92be8c7fc8f7" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019c5355-1f66-7c36-a7ed-bcd1eceb58f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_ComponentsOfMedicalCareCostsAbstract_019c5355-1f66-71fc-b77b-e8bee7aa2f57" xlink:href="moh-20260331.xsd#moh_ComponentsOfMedicalCareCostsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019c5355-1f66-7471-8903-92be8c7fc8f7" xlink:to="loc_moh_ComponentsOfMedicalCareCostsAbstract_019c5355-1f66-71fc-b77b-e8bee7aa2f57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense_019c5355-1f66-70a2-8d26-0d1eebf3b972" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_ComponentsOfMedicalCareCostsAbstract_019c5355-1f66-71fc-b77b-e8bee7aa2f57" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense_019c5355-1f66-70a2-8d26-0d1eebf3b972" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_019c5355-1f66-7e8c-a37b-bc2b0e1ab022" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_ComponentsOfMedicalCareCostsAbstract_019c5355-1f66-71fc-b77b-e8bee7aa2f57" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_019c5355-1f66-7e8c-a37b-bc2b0e1ab022" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_019c5355-1f66-7846-bd89-f18d7355ac5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_ComponentsOfMedicalCareCostsAbstract_019c5355-1f66-71fc-b77b-e8bee7aa2f57" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_019c5355-1f66-7846-bd89-f18d7355ac5c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_PaymentsForMedicalCareCostsAbstract_019c5355-1f66-7db3-b8f3-a43f357475a5" xlink:href="moh-20260331.xsd#moh_PaymentsForMedicalCareCostsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019c5355-1f66-7471-8903-92be8c7fc8f7" xlink:to="loc_moh_PaymentsForMedicalCareCostsAbstract_019c5355-1f66-7db3-b8f3-a43f357475a5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1_019c5355-1f66-7570-b3f3-e79dee9db213" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_PaymentsForMedicalCareCostsAbstract_019c5355-1f66-7db3-b8f3-a43f357475a5" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1_019c5355-1f66-7570-b3f3-e79dee9db213" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1_019c5355-201b-7e22-83ac-0ae52d4fcc2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_PaymentsForMedicalCareCostsAbstract_019c5355-1f66-7db3-b8f3-a43f357475a5" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1_019c5355-201b-7e22-83ac-0ae52d4fcc2a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_019c5355-201b-7f2c-a6ad-7e0fd41aa4b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForLossesAndLossAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_PaymentsForMedicalCareCostsAbstract_019c5355-1f66-7db3-b8f3-a43f357475a5" xlink:to="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_019c5355-201b-7f2c-a6ad-7e0fd41aa4b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitionsNetOfPostClosingAdjustments_019c5355-201b-7e67-bc36-c9cb6f9944d0" xlink:href="moh-20260331.xsd#moh_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitionsNetOfPostClosingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019c5355-1f66-7471-8903-92be8c7fc8f7" xlink:to="loc_moh_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseBusinessAcquisitionsNetOfPostClosingAdjustments_019c5355-201b-7e67-bc36-c9cb6f9944d0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicalClaimsAndBenefitsPayableAdjustmentsChangeInProvider_019c5355-201b-7879-aaad-82d9355ffc6f" xlink:href="moh-20260331.xsd#moh_MedicalClaimsAndBenefitsPayableAdjustmentsChangeInProvider"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNetAbstract_019c5355-1f66-7471-8903-92be8c7fc8f7" xlink:to="loc_moh_MedicalClaimsAndBenefitsPayableAdjustmentsChangeInProvider_019c5355-201b-7879-aaad-82d9355ffc6f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019c5355-201b-7d41-b078-5736baa40dd1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/DebtScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#DebtScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/DebtScheduleofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019c5355-201b-74a0-9d01-7e079d8a5791" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7830-81cc-7c9b8dc18706" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019c5355-201b-74a0-9d01-7e079d8a5791" xlink:to="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7830-81cc-7c9b8dc18706" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019c5355-201b-78d0-a55c-bc2e8df1a942" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7830-81cc-7c9b8dc18706" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019c5355-201b-78d0-a55c-bc2e8df1a942" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019c5355-201b-78d0-a55c-bc2e8df1a942_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019c5355-201b-78d0-a55c-bc2e8df1a942" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019c5355-201b-78d0-a55c-bc2e8df1a942_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019c5355-201b-76b8-af68-46fd76d95945" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019c5355-201b-78d0-a55c-bc2e8df1a942" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019c5355-201b-76b8-af68-46fd76d95945" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019c5355-201b-7fd3-961a-637e983afc7c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019c5355-201b-76b8-af68-46fd76d95945" xlink:to="loc_us-gaap_SeniorNotesMember_019c5355-201b-7fd3-961a-637e983afc7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019c5355-201b-731c-a678-5a150c2b7a98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7830-81cc-7c9b8dc18706" xlink:to="loc_us-gaap_DebtInstrumentAxis_019c5355-201b-731c-a678-5a150c2b7a98" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-731c-a678-5a150c2b7a98_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019c5355-201b-731c-a678-5a150c2b7a98" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-731c-a678-5a150c2b7a98_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-7f0e-8507-cba466918919" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019c5355-201b-731c-a678-5a150c2b7a98" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-7f0e-8507-cba466918919" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A4.375SeniorNotesDue2028Member_019c5355-201b-7e0b-9847-324ae18502d6" xlink:href="moh-20260331.xsd#moh_A4.375SeniorNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-7f0e-8507-cba466918919" xlink:to="loc_moh_A4.375SeniorNotesDue2028Member_019c5355-201b-7e0b-9847-324ae18502d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A3.875SeniorNotesDue2030Member_019c5355-201b-79bc-a26b-78dd8376a9df" xlink:href="moh-20260331.xsd#moh_A3.875SeniorNotesDue2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-7f0e-8507-cba466918919" xlink:to="loc_moh_A3.875SeniorNotesDue2030Member_019c5355-201b-79bc-a26b-78dd8376a9df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A6.500SeniorNotesDue2031Member_019cddba-5fe3-7046-8c97-638e433257f8" xlink:href="moh-20260331.xsd#moh_A6.500SeniorNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-7f0e-8507-cba466918919" xlink:to="loc_moh_A6.500SeniorNotesDue2031Member_019cddba-5fe3-7046-8c97-638e433257f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A3.875SeniorNotesDue2032Member_019c5355-201b-7cd7-a42d-310aea63336b" xlink:href="moh-20260331.xsd#moh_A3.875SeniorNotesDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-7f0e-8507-cba466918919" xlink:to="loc_moh_A3.875SeniorNotesDue2032Member_019c5355-201b-7cd7-a42d-310aea63336b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_A6.250SeniorNotesDue2033Member_019c5355-201b-71ae-9c36-821d7367104c" xlink:href="moh-20260331.xsd#moh_A6.250SeniorNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019c5355-201b-7f0e-8507-cba466918919" xlink:to="loc_moh_A6.250SeniorNotesDue2033Member_019c5355-201b-71ae-9c36-821d7367104c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019c5355-201b-754b-b9ca-00c91fd8ff35" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019c5355-201b-74a0-9d01-7e079d8a5791" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019c5355-201b-754b-b9ca-00c91fd8ff35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_LongTermDebtNoncurrentNetOfUnamortizedDebtDiscount_019c5355-201b-7f85-865e-e692f99b8538" xlink:href="moh-20260331.xsd#moh_LongTermDebtNoncurrentNetOfUnamortizedDebtDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019c5355-201b-74a0-9d01-7e079d8a5791" xlink:to="loc_moh_LongTermDebtNoncurrentNetOfUnamortizedDebtDiscount_019c5355-201b-7f85-865e-e692f99b8538" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019c5355-201b-729e-af63-59f169402cb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019c5355-201b-74a0-9d01-7e079d8a5791" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019c5355-201b-729e-af63-59f169402cb4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019c5355-201b-7672-91a0-bebd4d64f389" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019c5355-201b-74a0-9d01-7e079d8a5791" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019c5355-201b-7672-91a0-bebd4d64f389" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7bab-9cb8-34450e7b9fb3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:to="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7bab-9cb8-34450e7b9fb3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019cddc7-4810-7e6f-a65a-b413585cdcc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7bab-9cb8-34450e7b9fb3" xlink:to="loc_us-gaap_CreditFacilityAxis_019cddc7-4810-7e6f-a65a-b413585cdcc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019cddc7-4810-7e6f-a65a-b413585cdcc2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019cddc7-4810-7e6f-a65a-b413585cdcc2" xlink:to="loc_us-gaap_CreditFacilityDomain_019cddc7-4810-7e6f-a65a-b413585cdcc2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019cddc7-4810-7268-902e-2d537d3b8cb8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019cddc7-4810-7e6f-a65a-b413585cdcc2" xlink:to="loc_us-gaap_CreditFacilityDomain_019cddc7-4810-7268-902e-2d537d3b8cb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019cddc7-4810-702a-9053-1fc9dedf4af7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019cddc7-4810-7268-902e-2d537d3b8cb8" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019cddc7-4810-702a-9053-1fc9dedf4af7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_SwinglineSubFacilityMember_019cddc7-4810-7ce3-b386-dc4fbedfa8c0" xlink:href="moh-20260331.xsd#moh_SwinglineSubFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019cddc7-4810-7268-902e-2d537d3b8cb8" xlink:to="loc_moh_SwinglineSubFacilityMember_019cddc7-4810-7ce3-b386-dc4fbedfa8c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_LetterOfCreditSubFacilityMember_019cddc7-4810-7de7-af28-eadb5a810785" xlink:href="moh-20260331.xsd#moh_LetterOfCreditSubFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019cddc7-4810-7268-902e-2d537d3b8cb8" xlink:to="loc_moh_LetterOfCreditSubFacilityMember_019cddc7-4810-7de7-af28-eadb5a810785" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019cddc7-4810-73b1-9bdf-58fa4a60fe1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7bab-9cb8-34450e7b9fb3" xlink:to="loc_us-gaap_DebtInstrumentAxis_019cddc7-4810-73b1-9bdf-58fa4a60fe1a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cddc7-4810-73b1-9bdf-58fa4a60fe1a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cddc7-4810-73b1-9bdf-58fa4a60fe1a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cddc7-4810-73b1-9bdf-58fa4a60fe1a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cddc7-4810-719f-af25-75054cf1b5a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cddc7-4810-73b1-9bdf-58fa4a60fe1a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cddc7-4810-719f-af25-75054cf1b5a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_NewCreditAgreementMember_019cddc7-4810-758b-ac95-d9b31a25dfe9" xlink:href="moh-20260331.xsd#moh_NewCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cddc7-4810-719f-af25-75054cf1b5a9" xlink:to="loc_moh_NewCreditAgreementMember_019cddc7-4810-758b-ac95-d9b31a25dfe9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_TermLoanMember_019cddc7-4810-72a5-8a80-4e5de45e8652" xlink:href="moh-20260331.xsd#moh_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cddc7-4810-719f-af25-75054cf1b5a9" xlink:to="loc_moh_TermLoanMember_019cddc7-4810-72a5-8a80-4e5de45e8652" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019cddc7-4810-7bde-81b9-f704f389470a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7bab-9cb8-34450e7b9fb3" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019cddc7-4810-7bde-81b9-f704f389470a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cddc7-4810-7bde-81b9-f704f389470a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cddc7-4810-7bde-81b9-f704f389470a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cddc7-4810-7bde-81b9-f704f389470a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cddc7-4810-7b27-b5c3-194476c40cd1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cddc7-4810-7bde-81b9-f704f389470a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cddc7-4810-7b27-b5c3-194476c40cd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019cddc7-4810-784a-9430-1ef6e9644eba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019cddc7-4810-7b27-b5c3-194476c40cd1" xlink:to="loc_us-gaap_LineOfCreditMember_019cddc7-4810-784a-9430-1ef6e9644eba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DelayedDrawTermLoanMember_019cddc7-4810-74aa-b100-eb3294a3302f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DelayedDrawTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019cddc7-4810-7b27-b5c3-194476c40cd1" xlink:to="loc_us-gaap_DelayedDrawTermLoanMember_019cddc7-4810-74aa-b100-eb3294a3302f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cddc7-4810-7336-9dc6-e8bd3502c788" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7bab-9cb8-34450e7b9fb3" xlink:to="loc_srt_RangeAxis_019cddc7-4810-7336-9dc6-e8bd3502c788" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cddc7-4810-7336-9dc6-e8bd3502c788_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cddc7-4810-7336-9dc6-e8bd3502c788" xlink:to="loc_srt_RangeMember_019cddc7-4810-7336-9dc6-e8bd3502c788_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cddc7-4810-79d4-b5e3-cb6fe75d7951" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cddc7-4810-7336-9dc6-e8bd3502c788" xlink:to="loc_srt_RangeMember_019cddc7-4810-79d4-b5e3-cb6fe75d7951" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cddc7-4810-7b81-92eb-b1f390ab2060" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cddc7-4810-79d4-b5e3-cb6fe75d7951" xlink:to="loc_srt_MinimumMember_019cddc7-4810-7b81-92eb-b1f390ab2060" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cddc7-4810-7f9c-ba7d-e6307ea346c4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cddc7-4810-79d4-b5e3-cb6fe75d7951" xlink:to="loc_srt_MaximumMember_019cddc7-4810-7f9c-ba7d-e6307ea346c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentCovenantPeriodAxis_019cddc7-4810-7068-bcd6-1726a45870ea" xlink:href="moh-20260331.xsd#moh_DebtInstrumentCovenantPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019c5355-201b-7bab-9cb8-34450e7b9fb3" xlink:to="loc_moh_DebtInstrumentCovenantPeriodAxis_019cddc7-4810-7068-bcd6-1726a45870ea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentCovenantPeriodDomain_019cddc7-4810-7068-bcd6-1726a45870ea_default" xlink:href="moh-20260331.xsd#moh_DebtInstrumentCovenantPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_moh_DebtInstrumentCovenantPeriodAxis_019cddc7-4810-7068-bcd6-1726a45870ea" xlink:to="loc_moh_DebtInstrumentCovenantPeriodDomain_019cddc7-4810-7068-bcd6-1726a45870ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentCovenantPeriodDomain_019cddc7-4810-78ec-b44d-71f669752359" xlink:href="moh-20260331.xsd#moh_DebtInstrumentCovenantPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_moh_DebtInstrumentCovenantPeriodAxis_019cddc7-4810-7068-bcd6-1726a45870ea" xlink:to="loc_moh_DebtInstrumentCovenantPeriodDomain_019cddc7-4810-78ec-b44d-71f669752359" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CovenantPeriodOneMember_019cddc7-4810-7d9c-900f-b2bf7ed83ae6" xlink:href="moh-20260331.xsd#moh_CovenantPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_DebtInstrumentCovenantPeriodDomain_019cddc7-4810-78ec-b44d-71f669752359" xlink:to="loc_moh_CovenantPeriodOneMember_019cddc7-4810-7d9c-900f-b2bf7ed83ae6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CovenantPeriodTwoMember_019cddc7-4810-7728-b777-ec2f3b72856d" xlink:href="moh-20260331.xsd#moh_CovenantPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_DebtInstrumentCovenantPeriodDomain_019cddc7-4810-78ec-b44d-71f669752359" xlink:to="loc_moh_CovenantPeriodTwoMember_019cddc7-4810-7728-b777-ec2f3b72856d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CovenantPeriodThreeMember_019cddc7-4810-768c-b0c0-b4985d3109d4" xlink:href="moh-20260331.xsd#moh_CovenantPeriodThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_DebtInstrumentCovenantPeriodDomain_019cddc7-4810-78ec-b44d-71f669752359" xlink:to="loc_moh_CovenantPeriodThreeMember_019cddc7-4810-768c-b0c0-b4985d3109d4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CovenantPeriodFourMember_019cddc7-4810-7764-b7b0-4cde0ebf95f2" xlink:href="moh-20260331.xsd#moh_CovenantPeriodFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_moh_DebtInstrumentCovenantPeriodDomain_019cddc7-4810-78ec-b44d-71f669752359" xlink:to="loc_moh_CovenantPeriodFourMember_019cddc7-4810-7764-b7b0-4cde0ebf95f2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019cddc7-4810-77d5-9f0e-b16a33d44e2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:to="loc_us-gaap_LineOfCredit_019cddc7-4810-77d5-9f0e-b16a33d44e2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019cddc7-4810-76d1-9914-7a4457ae300d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019cddc7-4810-76d1-9914-7a4457ae300d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019cddc7-4810-7b05-aad9-5de2b5e659f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019cddc7-4810-7b05-aad9-5de2b5e659f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_019cddc7-4810-713d-a9cb-57ebfaaa245b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:to="loc_us-gaap_DebtInstrumentTerm_019cddc7-4810-713d-a9cb-57ebfaaa245b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentCovenantInterestCoverageRatioMinimum_019cddc7-4810-71a5-89f9-f8891d56dd40" xlink:href="moh-20260331.xsd#moh_DebtInstrumentCovenantInterestCoverageRatioMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:to="loc_moh_DebtInstrumentCovenantInterestCoverageRatioMinimum_019cddc7-4810-71a5-89f9-f8891d56dd40" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentDebtToCapitalizationRatio_019cddc7-4810-7712-b657-f82745f590b9" xlink:href="moh-20260331.xsd#moh_DebtInstrumentDebtToCapitalizationRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:to="loc_moh_DebtInstrumentDebtToCapitalizationRatio_019cddc7-4810-7712-b657-f82745f590b9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_DebtInstrumentDebtToCapitalizationRatioCashConsiderationAmount_019cddc7-4810-7d72-8fdb-b14c8bb88570" xlink:href="moh-20260331.xsd#moh_DebtInstrumentDebtToCapitalizationRatioCashConsiderationAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cddc7-4810-7de0-8e3f-be8f39fd5ba5" xlink:to="loc_moh_DebtInstrumentDebtToCapitalizationRatioCashConsiderationAmount_019cddc7-4810-7d72-8fdb-b14c8bb88570" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.molinahealthcare.com/role/SegmentsReconciliationofGrossMargintoConsolidatedIncomeDetails" xlink:type="simple" xlink:href="moh-20260331.xsd#SegmentsReconciliationofGrossMargintoConsolidatedIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.molinahealthcare.com/role/SegmentsReconciliationofGrossMargintoConsolidatedIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019c5355-201b-7da4-8387-c58ff2a709fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019c5355-201b-7da4-8387-c58ff2a709fb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019c5355-201b-7638-8649-87d65d7aff44" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019c5355-201b-7da4-8387-c58ff2a709fb" xlink:to="loc_srt_ConsolidationItemsAxis_019c5355-201b-7638-8649-87d65d7aff44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019c5355-201b-7638-8649-87d65d7aff44_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019c5355-201b-7638-8649-87d65d7aff44" xlink:to="loc_srt_ConsolidationItemsDomain_019c5355-201b-7638-8649-87d65d7aff44_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019c5355-201b-77db-8521-f3498fbf5192" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019c5355-201b-7638-8649-87d65d7aff44" xlink:to="loc_srt_ConsolidationItemsDomain_019c5355-201b-77db-8521-f3498fbf5192" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019c5355-201b-703e-8534-57d8586cb234" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019c5355-201b-77db-8521-f3498fbf5192" xlink:to="loc_us-gaap_OperatingSegmentsMember_019c5355-201b-703e-8534-57d8586cb234" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-201b-7e46-a7d0-9d2f690ab45c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019c5355-201b-7da4-8387-c58ff2a709fb" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-201b-7e46-a7d0-9d2f690ab45c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019c5355-201b-7e46-a7d0-9d2f690ab45c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-201b-7e46-a7d0-9d2f690ab45c" xlink:to="loc_us-gaap_SegmentDomain_019c5355-201b-7e46-a7d0-9d2f690ab45c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019c5355-201b-7cdc-9eb7-b25cc8d2857d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019c5355-201b-7e46-a7d0-9d2f690ab45c" xlink:to="loc_us-gaap_SegmentDomain_019c5355-201b-7cdc-9eb7-b25cc8d2857d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicaidMember_019c5355-201b-7607-abb3-fb934992534e" xlink:href="moh-20260331.xsd#moh_MedicaidMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-201b-7cdc-9eb7-b25cc8d2857d" xlink:to="loc_moh_MedicaidMember_019c5355-201b-7607-abb3-fb934992534e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicareMember_019c5355-201b-7ac6-a40f-5eb1d0bacbf8" xlink:href="moh-20260331.xsd#moh_MedicareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-201b-7cdc-9eb7-b25cc8d2857d" xlink:to="loc_moh_MedicareMember_019c5355-201b-7ac6-a40f-5eb1d0bacbf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MarketplaceMember_019c5355-201b-78c9-93c9-32f653c3a013" xlink:href="moh-20260331.xsd#moh_MarketplaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-201b-7cdc-9eb7-b25cc8d2857d" xlink:to="loc_moh_MarketplaceMember_019c5355-201b-78c9-93c9-32f653c3a013" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_OtherProgramMember_019c5355-201b-7fa6-a301-e4433ac70bce" xlink:href="moh-20260331.xsd#moh_OtherProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019c5355-201b-7cdc-9eb7-b25cc8d2857d" xlink:to="loc_moh_OtherProgramMember_019c5355-201b-7fa6-a301-e4433ac70bce" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019c5355-201b-7fdf-b7be-9845fdd5b526" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019c5355-201b-7da4-8387-c58ff2a709fb" xlink:to="loc_srt_ProductOrServiceAxis_019c5355-201b-7fdf-b7be-9845fdd5b526" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019c5355-201b-7fdf-b7be-9845fdd5b526_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019c5355-201b-7fdf-b7be-9845fdd5b526" xlink:to="loc_srt_ProductsAndServicesDomain_019c5355-201b-7fdf-b7be-9845fdd5b526_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019c5355-201b-7f46-9f6a-d2ca197f9369" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019c5355-201b-7fdf-b7be-9845fdd5b526" xlink:to="loc_srt_ProductsAndServicesDomain_019c5355-201b-7f46-9f6a-d2ca197f9369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_MedicalMember_019c5355-201b-7216-8027-be485e35a8ce" xlink:href="moh-20260331.xsd#moh_MedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019c5355-201b-7f46-9f6a-d2ca197f9369" xlink:to="loc_moh_MedicalMember_019c5355-201b-7216-8027-be485e35a8ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_019c5355-201b-7eb8-9826-56dd7cf48c28" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019c5355-201b-7f46-9f6a-d2ca197f9369" xlink:to="loc_us-gaap_ServiceMember_019c5355-201b-7eb8-9826-56dd7cf48c28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_019c5355-201b-7a5d-8882-e09e28f844ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_RevenuesAbstract_019c5355-201b-7a5d-8882-e09e28f844ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsEarnedNet_019c5355-201b-7a05-b156-088bbf9b5def" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_019c5355-201b-7a5d-8882-e09e28f844ac" xlink:to="loc_us-gaap_PremiumsEarnedNet_019c5355-201b-7a05-b156-088bbf9b5def" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_ServiceRevenue_019c5355-201b-7c1d-b73c-e2f9f6a42b92" xlink:href="moh-20260331.xsd#moh_ServiceRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_019c5355-201b-7a5d-8882-e09e28f844ac" xlink:to="loc_moh_ServiceRevenue_019c5355-201b-7c1d-b73c-e2f9f6a42b92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_PremiumsEarnedAndServiceRevenue_019c5355-201b-745a-9287-7ff1a16edfba" xlink:href="moh-20260331.xsd#moh_PremiumsEarnedAndServiceRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_moh_PremiumsEarnedAndServiceRevenue_019c5355-201b-745a-9287-7ff1a16edfba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncome_019c5355-201b-72ce-bce2-3a45ce48bb78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_OtherOperatingIncome_019c5355-201b-72ce-bce2-3a45ce48bb78" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019c5355-201b-7bf3-b93e-1597bf5235ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_Revenues_019c5355-201b-7bf3-b93e-1597bf5235ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_019c5355-201b-7943-91e3-eb4ae2b67e9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_019c5355-201b-7943-91e3-eb4ae2b67e9f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019c5355-201b-7c43-985e-c4087a4a2d43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019c5355-201b-7943-91e3-eb4ae2b67e9f" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019c5355-201b-7c43-985e-c4087a4a2d43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_CostOfServiceRevenue_019c5355-201b-72b5-a753-0aeec5d6161a" xlink:href="moh-20260331.xsd#moh_CostOfServiceRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019c5355-201b-7943-91e3-eb4ae2b67e9f" xlink:to="loc_moh_CostOfServiceRevenue_019c5355-201b-72b5-a753-0aeec5d6161a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_moh_SegmentExpenses_019c5355-201b-7f06-9da4-f1ef48429e55" xlink:href="moh-20260331.xsd#moh_SegmentExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_moh_SegmentExpenses_019c5355-201b-7f06-9da4-f1ef48429e55" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherExpenses_019c5355-201b-751d-bc32-c89a1c12d2e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_OtherExpenses_019c5355-201b-751d-bc32-c89a1c12d2e7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019c5355-201b-790b-8c57-3301c5554d34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_OperatingIncomeLoss_019c5355-201b-790b-8c57-3301c5554d34" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019c5355-201b-7eb5-abec-8dc1f97265ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019c5355-201b-7eb5-abec-8dc1f97265ff" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019c5355-201b-763b-aa98-b95f3f3fdb3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019c5355-201b-763b-aa98-b95f3f3fdb3c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_019c5355-201b-7cfa-9ce2-0fcbd9200b0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019c5355-201b-7e66-b167-52e36abd682e" xlink:to="loc_us-gaap_GrossProfit_019c5355-201b-7cfa-9ce2-0fcbd9200b0f" xlink:type="arc" order="10"/>
  </link:definitionLink>
</link:linkbase>