X0609 4 2026-06-09 0 0001835830 Klaviyo, Inc. KVYO 0001673606 St. Ledger Susan false C/O KLAVIYO, INC. 125 SUMMER STREET, 6TH FLOOR BOSTON MA 02110 1 0 0 0 0 Series A Common Stock 2026-06-09 4 A 0 14822 0 A 25761 D Represents restricted stock units ("RSUs") awarded under the Issuer's 2023 Stock Option and Incentive Plan, each representing the contingent right to receive one share of the Issuer's Series A Common Stock, par value $0.001 per share ("Series A Common Stock"), upon vesting and settlement. The RSUs vest in full upon the earlier of (i) June 9, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, in each case subject to the Reporting Person's continued service as a member of the Issuer's board of directors through such vesting date. Consists of (i) 10,939 shares of Series A Common Stock and (ii) 14,822 unvested RSUs awarded under the Issuer's 2023 Stock Option and Incentive Plan, each representing the contingent right to receive one share of Series A Common Stock upon vesting and settlement. /s/ Landon Edmond, Attorney-in-Fact 2026-06-11