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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-02-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002009787</rptOwnerCik>
            <rptOwnerName>Brunner Steven H</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 Risk Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-02-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1558</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1558</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-02-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>518</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5265</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-02-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1876</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>49.85</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3389</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1630</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>498</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F6"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1244</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F7"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">1,558 shares of Bankwell Financial Group, Inc. stock granted pursuant to the 2022 Bankwell Financial Group, Inc. Stock Plan. 779 of those shares are restricted stock that will vest in three substantially equal annual installments, with the first installment to vest on February 7, 2027 and the second and third installments to vest on each annual anniversary of the vesting date thereafter. 779 of those shares are performance restricted stock with a three year cliff vesting on February 7, 2029 if the performance goal is achieved.</footnote>
        <footnote id="F2">518 shares were granted and vested on February 9, 2026. These shares were related to 2023, 2024, and 2025 additional performance shares.</footnote>
        <footnote id="F3">Range of reported sale price is $49.52 - $50.26. Reporting person agrees to provide individual transaction information to SEC upon request.</footnote>
        <footnote id="F4">1,876 shares were withheld and sold through the Company sponsored cashless stock exercise program, to cover the tax liability for vesting a total of 3,717 shares.</footnote>
        <footnote id="F5">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, 1,632 restricted shares have vested, 816 performance shares vested, and 542 performance shares have been forfeited. 282 additional performance shares vested.</footnote>
        <footnote id="F6">498  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="F7">1,493 shares of Bankwell Financial Group, Inc. stock granted pursuant to the 2022 Bankwell Financial Group, Inc. Stock Plan. 746 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. 746 of those shares are performance restricted stock with a three year cliff vesting on February 7, 2028 if the performance goals are achieved. As of the vesting date, 249 shares have vested.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Steven H. Brunner</signatureName>
        <signatureDate>2026-02-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
