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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-08-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000730708</issuerCik>
        <issuerName>SEACOAST BANKING CORP OF FLORIDA</issuerName>
        <issuerTradingSymbol>SBCF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001916396</rptOwnerCik>
            <rptOwnerName>STALLINGS JAMES C III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 9012</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>STUART</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>34995</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, Chief Credit Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-08-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2990</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>23.7809</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7805</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3703</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Weighted average price. These shares were sold in multiple transactions at prices ranging from $23.770 to $23.795 inclusive. 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 above.</footnote>
        <footnote id="F2">Represents an unvested time-based restricted stock award granted on April 1, 2022, which shall vest over 3 years in one-third increments, beginning April 1, 2023, and on each anniversary thereafter, subject to continued employment</footnote>
        <footnote id="F3">Represents an unvested time-based restricted stock award granted on April 1, 2023, which shall vest over 3 years in one-third increments, beginning April 1, 2024, and on each anniversary thereafter, subject to continued employment</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Kathy L. Hsu as Power of Attorney for James C. Stallings, III</signatureName>
        <signatureDate>2023-08-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2023-08-04
0
0000730708
SEACOAST BANKING CORP OF FLORIDA
SBCF
0001916396
STALLINGS JAMES C III
P.O. BOX 9012
STUART
FL
34995
0
1
0
0
EVP, Chief Credit Officer
0
Common Stock
2023-08-04
4
S
0
2990
23.7809
D
0
D
Common Stock
7805
D
Common Stock
3703
D
Weighted average price. These shares were sold in multiple transactions at prices ranging from $23.770 to $23.795 inclusive. 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 above.
Represents an unvested time-based restricted stock award granted on April 1, 2022, which shall vest over 3 years in one-third increments, beginning April 1, 2023, and on each anniversary thereafter, subject to continued employment
Represents an unvested time-based restricted stock award granted on April 1, 2023, which shall vest over 3 years in one-third increments, beginning April 1, 2024, and on each anniversary thereafter, subject to continued employment
/s/ Kathy L. Hsu as Power of Attorney for James C. Stallings, III
2023-08-07