<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-04-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001103838</issuerCik>
        <issuerName>ICICI BANK LTD</issuerName>
        <issuerTradingSymbol>IBN</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002119583</rptOwnerCik>
            <rptOwnerName>Bakhshi Sandeep</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>ICICI BANK TOWERS</rptOwnerStreet1>
            <rptOwnerStreet2>BANDRA-KURLA COMPLEX</rptOwnerStreet2>
            <rptOwnerCity>MUMBAI</rptOwnerCity>
            <rptOwnerNonUSStateTerritory>K7</rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>K7</rptOwnerCountry>
            <rptOwnerZipCode>400051</rptOwnerZipCode>
            <rptOwnerStateDescription>INDIA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Equity Shares, par value Rs. 2 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2026-04-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>24999</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.95</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1071301</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The sale prices (average) of the shares are denominated in Rupee and translated for convenience only into USD at the rate of INR92.90 to US$1.00, the exchange rate set forth in the H.10 statistical release of the Federal Reserve Board on April 17, 2026.</footnote>
        <footnote id="F2">The price reported in Column 4 is an average price. These shares were sold in multiple transactions at prices ranging from $14.91 to $14.96. The Reporting Person undertakes to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Vivek Ranjan, as Attorney-in-fact</signatureName>
        <signatureDate>2026-04-24</signatureDate>
    </ownerSignature>
</ownershipDocument>