Signature of Stockholder Date: Signature of Stockholder Date: Note: Please sign exactly as your name or names appear on this Proxy. When shares are held jointly, each holder should sign. When signing as executor, administrator, attorney, trustee or guardian, please give full title as such. If the signer is a corporation, please sign full corporate name by duly authorized officer, giving full title as such. If signer is a partnership, please sign in partnership name by authorized person. To change the address on your account, please check the box at right and indicate your new address in the address space above. Please note that changes to the registered name(s) on the account may not be submitted via this method. INSTRUCTIONS: To withhold authority to vote for any individual nominee(s), mark “FOR ALL EXCEPT” and fill in the circle next to each nominee you wish to withhold, as shown here: JOHN SMITH 1234 MAIN STREET APT. 203 NEW YORK, NY 10038 PROXY VOTING INSTRUCTIONS Please detach along perforated line and mail in the envelope provided IF you are not voting via telephone or the Internet. THE BOARD OF DIRECTORS RECOMMENDS A VOTE "FOR" THE ELECTION OF DIRECTORS, FOR “1 YEAR” ON PROPOSAL 2 AND "FOR" PROPOSAL 3. PLEASE SIGN, DATE AND RETURN PROMPTLY IN THE ENCLOSED ENVELOPE. PLEASE MARK YOUR VOTE IN BLUE OR BLACK INK AS SHOWN HERE x 20340300000000001000 0 060123 COMPANY NUMBER ACCOUNT NUMBER MARK “X” HERE IF YOU PLAN TO ATTEND THE MEETING. ANNUAL MEETING OF STOCKHOLDERS OF DOUBLEVERIFY HOLDINGS, INC. June 1, 2023 1. Election of Directors: O R. DAVIS NOELL O LUCY STAMELL DOBRIN O TERI L. LIST FOR ALL NOMINEES WITHHOLD AUTHORITY FOR ALL NOMINEES FOR ALL EXCEPT (See instructions below) NOMINEES: NOTICE OF INTERNET AVAILABILITY OF PROXY MATERIAL: The Notice of Meeting, Proxy Statement and Proxy Card are available at https://ir.doubleverify.com/sec-filings/annual-report-proxy INTERNET - Access “www.voteproxy.com” and follow the on-screen instructions or scan the QR code with your smartphone. Have your proxy card available when you access the web page. TELEPHONE - Call toll-free 1-800-PROXIES (1-800-776-9437) in the United States or 1-718-921-8500 from foreign countries and follow the instructions. Have your proxy card available when you call. Vote online/phone until 11:59 PM EST the day before the meeting. MAIL - Sign, date and mail your proxy card in the envelope provided as soon as possible. VIRTUALLY AT THE MEETING - The company will be hosting the meeting live via the Internet. To attend the meeting via the Internet, please visit https://web.lumiagm.com/223761380 (password: doubleverify2023) and be sure to have your control number available. GO GREEN - e-Consent makes it easy to go paperless. With e-Consent, you can quickly access your proxy materials, statements and other eligible documents online, while reducing costs, clutter and paper waste. Enroll today via www.astfinancial.com to enjoy online access. 2. Non-binding advisory vote on the frequency of future stockholder advisory votes on the compensation of our named executive officers 3. Ratification of appointment of Deloitte & Touche LLP as independent registered public accounting firm for the fiscal year ending December 31, 2023. In their discretion, the proxies are authorized to vote upon such other business as may properly come before the Annual Meeting. This proxy when properly executed will be voted as directed herein by the undersigned shareholder. If no direction is made, this proxy will be voted FOR ALL NOMINEES in Proposal 1, for 1 YEAR on Proposal 2 and FOR Proposal 3. FOR AGAINST ABSTAIN 1 YEAR 2 YEARS 3 YEARS ABSTAIN

1. Election of Directors: R. DAVIS NOELL LUCY STAMELL DOBRIN TERI L. LIST 2. Non-binding advisory vote on the frequency of future stockholder advisory votes on the compensation of our named executive officers 3. Ratification of appointment of Deloitte & Touche LLP as independent registered public accounting firm for the fiscal year ending December 31, 2023. THE BOARD OF DIRECTORS RECOMMENDS A VOTE "FOR" THE ELECTION OF DIRECTORS, FOR “1 YEAR” ON PROPOSAL 2 AND "FOR" PROPOSAL 3. NOMINEES: This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. If you want to receive a paper or e-mail copy of the proxy materials you must request one. There is no charge to you for requesting a copy. To facilitate timely delivery please make the request as instructed below before 5/18/2023. Please visit https://ir.doubleverify.com/sec-filings/annual-report-proxy, where the following materials are available for view: • Notice of Annual Meeting of Stockholders • Proxy Statement • Form of Electronic Proxy Card • Annual Report TO REQUEST MATERIAL: TELEPHONE: 888-Proxy-NA (888-776-9962) 718-921-8562 (for international callers) E-MAIL: info@astfinancial.com WEBSITE: https://us.astfinancial.com/OnlineProxyVoting/ProxyVoting/RequestMaterials TO VOTE: ONLINE: To access your online proxy card, please visit www.voteproxy.com and follow the on-screen instructions or scan the QR code with your smartphone. You may enter your voting instructions at www.voteproxy.com up until 11:59 PM Eastern Time the day before the cut-off or meeting date. IN PERSON: You may vote your shares in person by attending the Annual Meeting. TELEPHONE: To vote by telephone, please visit www.voteproxy.com to view the materials and to obtain the toll free number to call. MAIL: You may request a card by following the instructions above. COMPANY NUMBER ACCOUNT NUMBER CONTROL NUMBER JOHN SMITH 1234 MAIN STREET APT. 203 NEW YORK, NY 10038 Please note that you cannot use this notice to vote by mail. Important Notice Regarding the Availability of Proxy Materials for the Stockholder Meeting of DOUBLEVERIFY HOLDINGS, INC. To Be Held On: June 1, 2023 virtually at https://web.lumiagm.com/223761380 (password: doubleverify2023)

¨	Preliminary Proxy Statement

¨	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

¨	Definitive Proxy Statement

x	Definitive Additional Materials

¨	Soliciting Material under Rule 14a-12

x	No fee required.

¨	Fee paid previously with preliminary materials.

¨	Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.