<SEC-DOCUMENT>0001628280-23-034904.txt : 20231023
<SEC-HEADER>0001628280-23-034904.hdr.sgml : 20231023
<ACCEPTANCE-DATETIME>20231023161542
ACCESSION NUMBER:		0001628280-23-034904
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20231023
FILED AS OF DATE:		20231023
DATE AS OF CHANGE:		20231023

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Fagnan Jeff
		CENTRAL INDEX KEY:			0001452366

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-41806
		FILM NUMBER:		231340149

	MAIL ADDRESS:	
		STREET 1:		56 WAREHAM STREET, FLOOR 3
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02118

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Accomplice Fund I, L.P.
		CENTRAL INDEX KEY:			0001636118
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-41806
		FILM NUMBER:		231340151

	BUSINESS ADDRESS:	
		STREET 1:		56 WAREHAM STREET, FLOOR 3
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02118
		BUSINESS PHONE:		617-588-2694

	MAIL ADDRESS:	
		STREET 1:		56 WAREHAM STREET, FLOOR 3
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02118

	FORMER NAME:	
		FORMER CONFORMED NAME:	F/K/A VENTURES FUND I, L.P.
		DATE OF NAME CHANGE:	20150310

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Accomplices Associates I, LLC
		CENTRAL INDEX KEY:			0001898737
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-41806
		FILM NUMBER:		231340150

	BUSINESS ADDRESS:	
		STREET 1:		56 WAREHAM STREET
		STREET 2:		3RD FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02118
		BUSINESS PHONE:		6175882600

	MAIL ADDRESS:	
		STREET 1:		56 WAREHAM STREET
		STREET 2:		3RD FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02118

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Moore Ryan R
		CENTRAL INDEX KEY:			0001810239

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-41806
		FILM NUMBER:		231340148

	MAIL ADDRESS:	
		STREET 1:		56 WAREHAM STREET
		STREET 2:		3RD FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02118

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Klaviyo, Inc.
		CENTRAL INDEX KEY:			0001835830
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		125 SUMMER STREET, FLOOR 6
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02110
		BUSINESS PHONE:		800-338-1744

	MAIL ADDRESS:	
		STREET 1:		125 SUMMER STREET, FLOOR 6
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02110
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1698092132.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-10-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001835830</issuerCik>
        <issuerName>Klaviyo, Inc.</issuerName>
        <issuerTradingSymbol>KVYO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001636118</rptOwnerCik>
            <rptOwnerName>Accomplice Fund I, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>56 WAREHAM STREET</rptOwnerStreet1>
            <rptOwnerStreet2>FLOOR 3</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02118</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001898737</rptOwnerCik>
            <rptOwnerName>Accomplices Associates I, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>56 WAREHAM STREET</rptOwnerStreet1>
            <rptOwnerStreet2>FLOOR 3</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02118</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001452366</rptOwnerCik>
            <rptOwnerName>Fagnan Jeff</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>56 WAREHAM STREET</rptOwnerStreet1>
            <rptOwnerStreet2>FLOOR 3</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02118</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001810239</rptOwnerCik>
            <rptOwnerName>Moore Ryan R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>56 WAREHAM STREET</rptOwnerStreet1>
            <rptOwnerStreet2>FLOOR 3</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02118</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Series A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-10-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>637049</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>28.3218</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>26720</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares were sold pursuant to the underwriters' partial exercise of their over-allotment option in connection with the initial public offering of the Issuer's Series A Common Stock at a net price per share of $28.3218, after underwriting discounts and commissions. Accomplice Fund I, L.P. was a selling stockholder in the initial public offering.</footnote>
        <footnote id="F2">Shares held by Accomplice Fund I, L.P. Accomplice Associates I, LLC is the general partner of Accomplice Fund I, L.P. Jeff Fagnan and Ryan Moore are Class A Members of Accomplice Associates I, LLC. Each Reporting Person disclaims beneficial ownership of the shares reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (&quot;Section 16&quot;), except to the extent of his or its pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Accomplice Fund I, L.P., By: Accomplice Associates I, LLC, Its: General Partner, By: /s/ Frank Castellucci, Secretary</signatureName>
        <signatureDate>2023-10-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Accomplice Associates I, LLC, By: /s/ Frank Castellucci, Secretary</signatureName>
        <signatureDate>2023-10-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Frank Castellucci, Attorney-in-Fact for Jeff Fagnan</signatureName>
        <signatureDate>2023-10-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Frank Castellucci, Attorney-in-Fact for Ryan Moore</signatureName>
        <signatureDate>2023-10-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
