MERCER INTERNATIONAL INC

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934 (Amendment No. )

Check the appropriate box:

(Name of Registrant as Specified In Its Charter)

N/A

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

NOTICE OF ANNUAL MEETING OF SHAREHOLDERS

The 2025 Annual Meeting (the "Annual Meeting") of shareholders ("Shareholders") of Mercer International Inc. (the "Company") will be held at Suite 1120, 700 West Pender Street, Vancouver, British Columbia, Canada on May 30, 2025 at 10:00 a.m. (Vancouver time) (doors open at 9:30 a.m. (Vancouver time)) for the following purposes:

To elect ten directors to serve until the 2026 annual meeting of Shareholders;

To approve, on a non-binding advisory basis, the compensation of the Company's executive officers as disclosed in these materials;

To ratify the selection of PricewaterhouseCoopers LLP as the Company's independent registered public accounting firm for fiscal year 2025;

To approve an amendment to the Mercer International Inc. Amended and Restated 2022 Stock Incentive Plan to increase the number of shares of common stock available for issuance under such plan; and

To transact such other business as may properly come before the Annual Meeting.

For those who are not able to attend in person, the Company is offering a virtual Shareholder meeting in which Shareholders may listen to the Annual Meeting, submit questions and vote online at: www.meetnow.global/MZDKCKM.

Only Shareholders of record at the close of business on March 27, 2025 will be entitled to notice of, and to vote at, the Annual Meeting or any adjournment, postponement or rescheduling thereof.

YOUR VOTE IS VERY IMPORTANT. Whether or not you plan to attend our Annual Meeting in person or through the virtual meeting, we urge you to cast your vote and submit your proxy as promptly as possible by one of the methods below. Make sure to have your proxy card or voting instruction form in hand. You do not need to attend the Annual Meeting to vote if you submitted your proxy in advance of the Annual Meeting. A proxy may be revoked in the manner described in the accompanying proxy statement.

For further information on how to vote, please refer to the instructions on the accompanying proxy card and the accompanying proxy statement.

BY ORDER OF THE BOARD OF DIRECTORS

/s/ William D. McCartney

William D. McCartney

Chairperson

April 15, 2025

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Shareholders to be held on May 30, 2025: Our proxy statement and our 2024 Annual Report to Shareholders are available at www.mercerint.com/investors/reports-filings/. Additionally, you may access our proxy materials atwww.proxyvote.com or www.investorvote.com/merc, a site that does not have "cookies" that identify visitors to the site.

PROXY STATEMENT

TABLE OF CONTENTS

iii