Osisko Development Appoints Vice President, Sustainable Development

ODV NYSE TSXV News Release

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OSISKO DEVELOPMENT APPOINTS VICE PRESIDENT, SUSTAINABLE DEVELOPMENT

Montreal, Québec, May 19, 2026 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko

Development" or the "Company") is pleased to announce the appointment of Mr. Greg Perrins as Vice

President, Sustainable Development, effective May 18, 2026.

"We are pleased to welcome Greg to the Osisko Development team, where his deep knowledge of and

experience in Indigenous relations and public sector engagement in BC will further strengthen our

approach to sustainable project development," stated Sean Roosen, Chairman and CEO.

Mr. Perrins is an Indigenous relations professional with over 15 years of experience in leadership roles

across the natural resource sector in British Columbia. Most recently , he served as Senior Manager,

Indigenous Relations at BC Hydro, a fully integrated public utility, where he supported engagement and

relationship-building initiatives with Indigenous Nations across the province. Prior to his role at BC

Hydro, Mr. Perrins spent the majority of his career working for the Province of British Columbia, including

roles with the Ministry of Energy, Mines and Low Carbon Innovation, the Ministry of Indigenous Relations

and Reconciliation , and the BC Oil and Gas Commission. Mr. Perrins holds a Master of Public

Administration degree from the University of Victoria, a Bachelor of Social Work degree from Dalhousie

University, and a Bachelor of Arts degree from the University of Regina.

ABOUT OSISKO DEVELOPMENT CORP.

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

producing mining camps with district -scale potential. The Company's objective is to become an

intermediate gold producer through the development of its flagship , fully permitted, 100%-owned

Cariboo Gold Project, located in central British Columbia, Canada. Its project pipeline is complemented

by the Tintic Project located in the historic East Tintic mining district in Utah, U.S.A ., a brownfield

property with si gnificant exploration potential, extensive historical mining data, and access to

established infrastructure. Osisko Development is focused on developing long -life mining assets in

mining-friendly jurisdictions while maintaining a disciplined approach to capital allocation, development

risk management, and mineral inventory growth.

For further information, 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

This news release contains "forward-looking information" (within the meaning of applicable Canadian securities laws) and "forward-

looking statements" (within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended) (collective ly,

"forward-looking statements"). Such forward -looking statements are identified with words such as "may", "will", "would", "could",

"anticipate", "believe", "expect", "plan", "intend", "potential", "estimate", "propose", "project", "outlook", "foresee" , "objective",

"strategy", variants of these words or the negative or comparable terminology, as well as terms usually used in the future and the

conditional. 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, limitations or statements

pertaining to: the ability to develop the Cariboo Gold Project and its status as being fully permitted ; the exploration potential and

prospectivity (if any) of its properties . Such forward -looking statements are based on a number of risks, uncertainties and

assumptions which may cause actual results or other expectations to differ materially from those anticipated and which may pr ove

to be incorrect. These assumptions include, but are not limited to: the absence of further work stopp ages or suspensions at the

Project; favourable regulatory conditions and approvals; the ability to maintain adequate personnel and contractor levels; th e

absence of unforeseen ground conditions or other geological challenges; the availability of necessary equipment, supplies and

infrastructure; and general economic and market conditions. Actual results could differ materially due to a number of factors ,

including, without limitation: risks related to the exploration, development and operation of the Cariboo Gold Project; health, safety

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and security incidents; regulatory delays or changes in regulatory framework and applicable laws; labour shortages or dispute s;

general economic and market conditions and business conditions in the mining industry; fluctuations in commodity and currency

exchange rates; changes in regulatory framework and applicable laws, as well as those risks and factors disclosed in the Company's

most recent annual information form, financial statements and management's discussion and analysis as well as other public fi lings

on SEDAR+ (www.sedarplus.ca) and on EDGAR (www.sec.gov). Although the Company believes the expectations conveyed by the

forward-looking statements are reasonable based on information available as of the date hereof, no assurances can be given as to

future results, 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, reade rs 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.