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

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-08-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000776901</issuerCik>
        <issuerName>INDEPENDENT BANK CORP</issuerName>
        <issuerTradingSymbol>INDB</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001405590</rptOwnerCik>
            <rptOwnerName>Nadeau Gerard F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O INDEPENDENT BANK CORP.</rptOwnerStreet1>
            <rptOwnerStreet2>288 UNION STREET</rptOwnerStreet2>
            <rptOwnerCity>ROCKLAND</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02370</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-08-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5307</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>84.6942</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16907</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>273.8589</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Daughter</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>276.2729</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Son</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $84.60 through $84.805 per share, inclusive. The Filer undertakes to provide Independent Bank Corp., any security holder of Independent Bank Corp., 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 footnote (1) to this Form 4.</footnote>
        <footnote id="F2">Shares held in Filer's name f/b/o daughter. Holdings include 2.1437 shares received pursuant to the Independent Bank Corp. 2014 Dividend Reinvestment and Stock Purchase Plan since the last Form 4 filing (05/21/26). Such transactions are exempt from the reporting requirements of Section 16 of the Securities and Exchange Act of 1934, as amended. The filing of this statement should not be construed as an admission that the Filer is, for purposes of Section 16 of the Exchange Act, the beneficial owner of such securities.</footnote>
        <footnote id="F3">Shares held in Filer's name f/b/o son. Holdings include 2.1626 shares received pursuant to the Independent Bank Corp. 2014 Dividend Reinvestment and Stock Purchase Plan since the last Form 4 filing (05/21/26). Such transactions are exempt from the reporting requirements of Section 16 of the Securities Exchange Act of 1934, as amended. The filing of this statement should not be construed as an admission that the Filer is, for purposes of Section 16 of the Exchange Act, the beneficial owner of such securities.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Maureen A. Gaffney, Power of Attorney for Gerard F. Nadeau</signatureName>
        <signatureDate>2026-08-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
