Osisko Development Corp. — Proxy Solicitation & Information Statement 2025

Apr 7, 2025

Osisko Development Corp. (the "Corporation")

Annual and Special Meeting
May 7, 2025 at 1:30 P.M. (Eastern Time)
1 Pl. Ville-Marie, Suite 2500, Montréal, Qc H3B 1R1
(the "Meeting")

OSISKO
DEVELOPMENT

Voting Instructions - Guidelines and Conditions

The Corporation is providing you the enclosed proxy-related materials for their securityholder Meeting. Your name, address and information about your security holdings have been obtained in accordance with applicable securities regulations from the intermediary holding them on your behalf (which is identified by name, code or identifier in the information on the top right corner on the reverse). The Voting Instruction Form ('VIF') is to enable your vote to be submitted on the stated matters. Please complete, sign, date and return the VIF. Unless you appoint yourself or a delegate to attend the Meeting and vote, your securities can be voted only by Management Nominees in accordance with your instructions.

We are prohibited from voting these securities on any of the matters to be acted upon at the Meeting without your specific voting instructions. In order for these securities to be voted at the meeting, it will be necessary for us to have your specific voting instructions. Please complete and return the information requested in this form to provide your voting instructions to us promptly. By providing voting instructions as requested, you are acknowledging that you are the beneficial owner of, and are entitled to instruct us with respect to the voting of, these securities.

THIS VOTING INSTRUCTION FORM SHOULD BE READ IN CONJUNCTION WITH THE MEETING MATERIAL. YOUR VOTING INSTRUCTIONS MUST BE RECEIVED NO LATER THAN THE FILING DEADLINE NOTED ON THE REVERSE OF THE VIF OR THE EQUIVALENT TIME BEFORE THE TIME AND DATE OF ANY ADJOURNMENT OR POSTPONEMENT OF THE MEETING.

Voting Instructions and Authority - Notes

1. THIS VOTING INSTRUCTION FORM IS SOLICITED BY OR ON BEHALF OF THE MANAGEMENT OF THE CORPORATION.
2. If you appoint the Management Nominees indicated on the reverse to vote your securities, they will vote in accordance with your instructions or, if no instructions are given, in accordance with the Voting Recommendation highlighted for each Resolution on the reverse. If you appoint someone else to vote your securities, they will also vote in accordance with your instructions or, if no instructions are given, as they in their discretion choose.
3. The appointment of the Management Nominees or another Appointee gives them discretion to vote on any other matters that may properly come before the Meeting.
4. If internet voting is available, you can provide your voting instructions on the website see "Internet" section under "Voting Method".
5. To be valid, this VIF must be signed. Please date the VIF. If the VIF is not dated, it is deemed to bear the date of mailing to the securityholders of the Corporation.
6. This form does not convey any right to vote in person at the Meeting. We urge you to read the above instructions, and the Information Circular prior to completing, signing and returning the VIF so that your securities can be voted. If you want to attend the meeting and vote in person, write your name in the place provided for that purpose on the reverse of this form. You can also write the name of someone else whom you wish to attend the meeting and vote on your behalf. Unless prohibited by law, the person whose name is written in the space provided will have full authority to present matters to the meeting and vote on all matters that are presented at the meeting, even if those matters are not set out in this form or the information circular. Consult a legal advisor if you wish to modify the authority of that person in any way. If you require help, contact your advisor.
7. Guidelines for proper execution of the VIF are available at www.stac.ca. Please refer to the Proxy Protocol.

Notice-and-Access

The Canadian securities regulators have adopted rules which permit the use of notice-and-access for proxy solicitation instead of the traditional physical delivery of material. This process provides the option to post meeting related materials including management information circulars as well as annual financial statements and management's discussion and analysis, on a website in addition to SEDAR+. Under notice-and-access, meeting related materials will be available for viewing for up to 1 year from the date of posting and a paper copy of the material can be requested at any time during this period.

Disclosure regarding each matter or group of matters to be voted on is in the Information Circular in the Section with the same title as each Resolution on the reverse. You should review the Information Circular before voting.

Osisko Development Corp. has elected to utilize notice-and-access and provide you with the following information:

Meeting materials are available electronically at www.sedarplus.ca and also at https://docs.tsxtrust.com/2355.

If you wish to receive a paper copy of the Meeting materials or have questions about notice-and-access, please call 1-866-600-5869. In order to receive a paper copy in time to vote before the Meeting, your request should be received by April 28, 2025.

VOTING METHOD
INTERNET	Go to www.voteproxyonline.com and enter the 12 digit control number
FACSIMILE	416-595-9593
MAIL or HAND DELIVERY	TSX Trust Company
301 - 100 Adelaide Street West
Toronto, Ontario, M5H 4H1
For assistance, please contact TSX TRUST INVESTOR SERVICES.
Mail: 301 - 100 Adelaide Street West Toronto, ON, M5H 4H1
Tel: 1-866-600-5869
Email: tsxtis@tmx.com

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TMX

TSX TRUST

VOTING INSTRUCTION FORM ("VIF")

Osisko Development Corp.

(the "Corporation")

Annual and Special Meeting

May 7, 2025 at 1:30 P.M. (Eastern Time)

1 Pl. Ville-Marie, Suite 2500, Montréal, Qc H3B 1R1

SECRITY CLASS: Common Shares

RECORD DATE: March 20, 2025

CONTROL NUMBER:

FILING DEADLINE FOR PROXY: May 5, 2025 at 1:30 P.M. (Eastern Time)

APPOINTEES

The undersigned hereby appoints Sean Roosen, Chair of the Board of Directors and Chief Executive Officer of the Corporation, whom failing Alexander Dann, CPA, CA, Chief Financial Officer and Vice-President Finance of the Corporation, or failing both of them Laurence Farmer, General Counsel and Vice-President Strategic Development of the Corporation (the "Management Nominees"), or instead of any of them, the following Appointee

Please print appointee name

as proxylolder on behalf of the undersigned with the power of substitution to attend, act and vote for and on behalf of the undersigned in respect of all matters that may properly come before the Meeting and at any adjournment(s) or postponement(s) thereof, to the same extent and with the same power as if the undersigned were personally present at the said Meeting or such adjournment(s) or postponement(s) thereof in accordance with voting instructions, if any, provided below.

• SEE VOTING GUIDELINES ON REVERSE -

RESOLUTIONS – VOTING RECOMMENDATIONS ARE INDICATED BY HIGHLIGHTED TEXT ABOVE THE BOXES

1. Election of Directors	FOR	AGAINST
a) Sean Roosen	☐	☐
b) Charles E. Page	☐	☐
c) Michèle McCarthy	☐	☐
d) Duncan Middlemiss	☐	☐
e) David Danziger	☐	☐
f) Stephen Quin	☐	☐
2. Appointment of Auditor	FOR	WITHHOLD
Appointment of PricewaterhouseCoopers LLP as Auditor of the Corporation for the ensuing year and authorizing the Directors to fix their remuneration.	☐	☐
3. Omnibus Plan	FOR	AGAINST
To consider and, if deemed appropriate, pass an ordinary resolution, the full text of which is set forth in the accompanying management information circular (the "Circular"), approving an omnibus equity incentive plan in the form attached as Appendix "C" to the Circular (the "Omnibus Plan Resolution").	☐	☐
4. Existing stock option plan	FOR	AGAINST
In the event the Omnibus Plan Resolution is not approved, to consider and, if deemed appropriate, pass an ordinary resolution, the full text of which is set forth in the Circular, approving the Corporation's existing stock option plan, as more particularly described in the Circular.	☐	☐
5. Existing restricted share unit plan with amendments	FOR	AGAINST
In the event the Omnibus Plan Resolution is not approved, to consider and, if deemed appropriate, pass an ordinary resolution, the full text of which is set forth in the Circular, approving the Corporation's existing restricted share unit plan with amendments thereto, as more particularly described in the Circular.	☐	☐

This VIF revokes and supersedes all earlier dated proxies and MUST BE SIGNED

PLEASE PRINT NAME	Signature of beneficial owner(s)	Date (MM/DD/YYYY)
☐ Interim Financial Statements – Mark this box if you would like to receive Interim Financial Statements and Management Discussion and Analysis.
If you are casting your vote online and wish to receive financial statements, please complete the online request for financial statements following your voting instructions. If the cut-off time has passed, please fax this side to 416-595-9593	☐ Annual Financial Statements – Mark this box if you would like to receive Annual Financial Statements and Management Discussion and Analysis.