Osisko Development to Complete Third Deferred Payment Installment IN Connection with the Tintic Acquisition; Engages Resource Stock Digest

ODV NYSE TSXV News Release

www.osiskodev.com Page 1 of 2

OSISKO DEVELOPMENT TO COMPLETE THIRD DEFERRED PAYMENT INSTALLMENT

IN CONNECTION WITH THE TINTIC ACQUISITION; ENGAGES RESOURCE STOCK

DIGEST

Montreal, Québec, May 29, 2025 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko

Development" or the "Company") announces that, in accordance with the terms of the Company's

previously-completed acquisition in May 2022 of a 100% ownership interest in the Tintic Project, located

in Utah, U.S.A., (the "Tintic Acquisition"), the Company intends to satisfy the third of five deferred

payments (the " Third Deferred Payment") to certain sellers of the Tintic Project (the " Sellers") in

common shares of the Company ("Common Shares").

The Third Deferred Payment of US$2,500,000 (or C$3,432,750 based on a USD/CAD exchange rate of

1.3731) is expected to be paid entirely in Common Shares at a deemed price of C$2.5082 per Common

Share (based on the 20 -day VWAP as of the closing of the market on May 26, 2025), resulting in the

issuance of 1,368,610 Common Shares to the Sellers in full satisfaction of the Third Deferred Payment.

The issuance of the Common Shares in satisfaction of the Third Deferred Payment remains subject to

the approval of the TSX Venture Exchange (the "Exchange").

For additional details regarding the Tintic Acquisition, please refer to the Company's news releases dated

January 25, 2022 (entitled "Osisko Development Announces Proposed Acquisition of Tintic Consolidated

Metals") and May 30, 2022 (entitled "Osisko Development Completes Acquisition of Tintic Consolidated

Metals, Finalizes Binding Stream Terms and Satisfies Escrow Release Condition For Brokered

Subscription Receipt Financing").

Marketing Services Agreement

The Company has entered into a marketing services agreement (the "Agreement") with Resource Stock

Digest ("RSD"), a company based out of Texas, effective June 1, 2025, pursuant to which, among other

things, RSD has agreed to provide certain promotional services to the Company in accordance with

Policy 3.4 – Investor Relations, Promotional and Market-Making Activities of the Exchange.

RSD has been engaged for a 6 -month advertising and marketing program for total cash consideration

of US$250,000, payable in two equal installments with the first of which due upon receipt of approval

of the Agreement by the Exchange. RSD conducts interviews with the Company and produces Company-

approved content that is distributed to RSD’s subscriber base an d connects issuers to the investment

community across North America.

There are no performance factors contained in the Agreement and RSD will not receive common shares

or options as compensation. Further, RSD and the Company are arm's length and, at the time of the

Agreement, neither RSD nor any of its principals have an interest, directly or indirectly, in the securities

of the Company.

The Agreement is subject to the approval of the Exchange. RSD is owned and operated by Gerardo Del

Real and Nick Hodge and its contact details are as follows: Gerardo Del Real, 2051 Gattis School Rd,

Ste. 540 PMB 176, Round Rock, TX 78664, USA; Email: [email protected]; Phone: (844)

334-4700.

www.osiskodev.com Page 2 of 2

ABOUT OSISKO DEVELOPMENT CORP.

Osisko Development Corp. is a North American gold development company focused on past -producing

mining camps located in mining friendly jurisdictions with district scale potential. The Company's

objective is to become an intermediate gold producer by advancing its flagship permitted 100%-owned

Cariboo Gold Project, located in central B.C., Canada. Its project pipeline is complemented by the Tintic

Project in the historic East Tintic mining district in Utah, U.S.A., and the San Antonio Gold Project in

Sonora, Mexico—brownfield properties with significant exploration potential, extensive historical mining

data, access to existing infrastructu re and skilled labour. The Company's strategy is to develop

attractive, long-life, socially and environmentally responsible mining assets, while minimizing exposure

to development risk and growing mineral resources.

For further information, visit our website at www.osiskodev.com or contact:

Sean Roosen Philip Rabenok

Chairman and CEO Vice President, Investor Relations

Email: [email protected] Email: [email protected]

Tel: +1 (514) 940-0685 Tel: +1 (437) 423-3644

CAUTION REGARDING FORWARD LOOKING STATEMENTS

Certain statements contained in this news release may be deemed "forward -looking statements" within the meaning of the United

States Private Securities Litigation Reform Act of 1995 and "forward-looking information" within the meaning of applicable Canadian

securities legislation (together, "forward -looking statements"). These forward -looking statements, by their nature, require Osisko

Development to make certain assumptions and necessarily involve known and unknown risks and uncertainties that could cause

actual results to differ materially from those expressed or implied in these forward-looking statements. Forward-looking statements

are not guarantees of performance. Words such as "may", "will", "would", "could", "expect", "believe", "plan", "anticipate", "intend",

"estimate", "continue", or the negative or comparable terminology, as well as terms usually used in the future and the condit ional,

are intended to identify forward -looking statements. Information contained in forward -looking statements is based upon certain

material assumptions that were applied in drawing a conclusion or making a forecast or projection, including the assumptions,

qualifications and limitations relating to the ability and timing of the Company to complete the Third Deferred Paym ent, to obtain

the Exchange's final approval of the issuance of the Common Shares in satisfaction of the Third Deferred Payment and to obtain the

Exchange's final approval of the Agreement. Although the Company's believes the expectations conveyed by the f orward-looking

statements are reasonable based on information available as of the date hereof, no assurances can be given as to future resul ts,

levels of activity and achievements. The Company disclaims any obligation to update any forward-looking statements, whether as a

result of new information, future events or results or otherwise, except as required by law. Forward -looking statements are not

guarantees of performance and there can be no assurance that these forward-looking statements will prove to be accurate, as actual

results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place

undue reliance on forward-looking statements.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the

TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this news release. No stock exchange,

securities commission or other regulatory authority has approved or disapproved the information contained herein.