SCHEDULE 13G

CUSIP No.

49845K101

Names of Reporting Persons

Bialecki Andrew

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 87,796,336.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 87,796,336.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

87,796,336.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

42.9 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

Item 1.

(a)

Name of issuer:

Klaviyo, Inc. (the "Issuer")

(b)

Address of issuer's principal executive offices:

125 Summer Street, 6th Floor, Boston, MA, 02110

Item 2.

(a)

Name of person filing:

This statement is filed on behalf of Andrew Bialecki (the "Reporting Person").

(b)

Address or principal business office or, if none, residence:

The business address of the Reporting Person is c/o Klaviyo, Inc., 125 Summer Street, 6th Floor, Boston, MA 02110.

(c)

Citizenship:

The Reporting Person is a citizen of the United States of America.

(d)

Title of class of securities:

Series A common stock, par value $0.001 per share (the "Series A Common Stock")

(e)

CUSIP No.:

49845K101

Item 3.

If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)

An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);

(f)

An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);

(g)

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:

(k)

Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).

Item 4.

Ownership

(a)

Amount beneficially owned:

The ownership information below represents beneficial ownership of Series A Common Stock of the Issuer as of June 30, 2025, based on (i) 116,877,930 shares of Series A Common Stock outstanding as of June 30, 2025, as reported by the Issuer to the Reporting Person, plus (ii) an aggregate of 87,796,336 shares of Series A Common Stock issuable upon conversion of shares of the Issuer's Series B common stock, par value $0.001 per share (the "Series B Common Stock"), beneficially owned by the Reporting Person, which are deemed outstanding pursuant to SEC Rule 13-3(d)(1)(i) only for purposes of computing the percentage ownership of the Reporting Person. The Reporting Person may be deemed to be the beneficial owner of 87,796,336 shares of Series A Common Stock, which includes: (i) 74,773,276 shares of Series A Common Stock underlying shares of Series B Common Stock held directly by the Reporting Person, (ii) 43,218 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Reporting Person's spouse, (iii) 11,945,830 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, of which the Reporting Person serves as trustee, (iv) 517,006 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Andrew P. Bialecki Irrevocable GST Trust of 2023, of which the Reporting Person's spouse serves as a trustee, and (v) 517,006 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Elizabeth L. Bialecki Irrevocable GST Trust of 2023, of which the Reporting Person serves as a trustee.

(b)

Percent of class:

42.9%

(c)

Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote:

87,796,336

(ii) Shared power to vote or to direct the vote:

(iii) Sole power to dispose or to direct the disposition of:

87,796,336

(iv) Shared power to dispose or to direct the disposition of:

Item 5.

Ownership of 5 Percent or Less of a Class.

Item 6.

Ownership of more than 5 Percent on Behalf of Another Person.

Not Applicable

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable

Item 8.

Identification and Classification of Members of the Group.

Not Applicable

Item 9.

Notice of Dissolution of Group.

Not Applicable

Item 10.

Certifications:

Not Applicable

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Bialecki Andrew

Signature:	/s/ Andrew Bialecki
Name/Title:	Andrew Bialecki
Date:	08/05/2025