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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-11-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001505732</issuerCik>
        <issuerName>Bankwell Financial Group, Inc.</issuerName>
        <issuerTradingSymbol>BWFG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001665699</rptOwnerCik>
            <rptOwnerName>Chivily Christine</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BANKWELL FINANCIAL GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>258 ELM STREET</rptOwnerStreet2>
            <rptOwnerCity>NEW CANAAN</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06840</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP &amp; Chief Credit Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-11-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2553</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>45.52</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13939</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1470</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>245</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>490</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3262</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1529</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">1,470 shares of Bankwell Financial Group, Inc. stock granted pursuant to the 2022 Bankwell Financial Group, Inc. Stock Plan. 735 of those shares are restricted stock that will vest in three substantially equal annual installments, with the first installment to vest on February 7, 2026 and the second and third installments to vest on each annual anniversary of the vesting date thereafter. 735 of those shares are performance restricted stock with a three year cliff vesting on February 7, 2028 if the performance goals are achieved.</footnote>
        <footnote id="F2">245 shares of Bankwell Financial Group, Inc. stock granted pursuant to the 2022 Bankwell Financial Group, Inc. Stock Plan. These shares are performance restricted stock with a one year cliff vesting on February 7, 2026 if the performance goals are achieved.</footnote>
        <footnote id="F3">490  shares of Bankwell Financial Group, Inc. stock granted pursuant to the 2022 Bankwell Financial Group, Inc. Stock Plan. These shares are performance restricted stock with a two year cliff vesting on February 7, 2027 if the performance goals are achieved.</footnote>
        <footnote id="F4">4,894 shares of Bankwell Financial Group, Inc. stock granted pursuant to the 2022 Bankwell Financial Group, Inc. Stock Plan. 2,447 of those shares are restricted stock that will vest in three substantially equal annual installments, with the first installment to vest on February 7, 2025 and the second and third installments to vest on each annual anniversary of the vesting date thereafter. 2,447 of those shares are performance restricted stock and may vest when and if the performance goal is achieved. As of the filing date, 1,090 shares have vested and 542 shares were forfeited.</footnote>
        <footnote id="F5">4,589 shares of Bankwell Financial Group, Inc. stock granted pursuant to the 2022 Bankwell Financial Group, Inc. Stock Plan. 2,295 of those shares are restricted stock that will vest in three substantially equal annual installments, with the first installment to vest on February 7, 2024 and the second and third installments to vest on each annual anniversary of the vesting date thereafter. 2,294 of those shares are performance restricted stock and may vest when and if the performance goal is achieved. As of the filing date, 2,295 shares have vested and 765 were forfeited.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Angelo G. Fusaro, Attorney-in-Fact for Christine Chivily</signatureName>
        <signatureDate>2025-11-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
