Osisko Development Strengthens Technical Team with Appointment of Vice President, Exploration

ODV NYSE TSXV News Release

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OSISKO DEVELOPMENT STRENGTHENS TECHNICAL TEAM WITH APPOINTMENT OF

VICE PRESIDENT, EXPLORATION

Montreal, Québec, November 3, 2025 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV)

("Osisko Development" or the "Company") is pleased to announce the appointment of Mr. Scott

Smith as Vice President, Exploration effective November 1, 2025 . Mr. Smith joins from Prime Mining

Corp. where he most recently served as Executive Vice President, Exploration until its acquisition by

Torex Gold Resources Inc. in October 2025.

"We are delighted to bolster our exploration team with Scott's appointment. He brings over 30 years of

extensive experience in the mining sector having worked on projects across the development spectrum,

and adds a complementary skill set to advance the vast exploration potential of the Cariboo Gold Project

and our other properties," commented Chris Lodder, President.

Mr. Scott Smith is a registered Professional Geologist with over 30 years of experience in mine

production, exploration, and advanced -stage mining projects across Canada, Mexico, Peru, Chile, and

the United States. Mr. Smith has spent more than 18 years in senior management roles , leading

geological teams in both mine production and exploration throughout North and South America ,

spanning operating mines, brownfields, and greenfield projects. Most recently, he served as Executive

Vice President of Exploration at Prime Mining Co rp., where he led resource extension and exploration

strategies for the Los Reyes Project in Mexico, delivering significant resource growth and contributing

to the company's successful sale to T orex Gold Resources Inc. Previously, he was Chief Geologist at

Gibraltar Mines Ltd. (2015 -2021), a major copper -molybdenum operation in central B ritish Columbia,

Canada. Earlier in his career, he managed exploration teams for Teck Resources Limited in Chile and

Argentina and led district geology teams with Newmont Corporation at Minera Yanacocha in Peru. He

also spent 5 years in operational roles with Compañía Minera Antamina in Peru, contribut ing to the

mine's startup and operational geology. Mr. Smith holds a B.Sc. in Geology from the University of Alberta

and is a registered Professional Geologist (P.Geo.) with APEGA in Canada.

ABOUT OSISKO DEVELOPMENT CORP.

Osisko Development Corp. is a continental 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 produ cer 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 infrastructure and skilled labour. The Company's strategy is to

develop attractive, long-life, socially and environmenta lly 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

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.