Mr. Sean Roosen reports

OSISKO DEVELOPMENT APPOINTS VICE PRESIDENT, PERMITTING AND COMPLIANCE

Osisko Development Corp. has appointed Sarah Harrison as vice-president, permitting and compliance, effective Feb. 2, 2026. Ms. Harrison joins Osisko Development from JDS Energy & Mining Inc., where she most recently held the position of project manager within its environmental division.

Ms. Harrison is a permitting and regulatory compliance professional with over 13 years of experience across environmental assessment, reclamation, permitting and regulatory compliance in the mining sector. Her experience spans the full mine development life cycle, from early-stage exploration through construction and operations, including major permit amendments for large-scale mining projects. Her recent roles include environmental manager supporting permitting and compliance activities at Artemis Gold Inc.'s Blackwater gold mine, an environmental compliance leadership role with Arctic Canadian Diamond Company, and regulatory experience with the British Columbia Environmental Assessment Office. Most recently, Ms. Harrison has advised a range of mining clients on navigating British Columbia's permitting and compliance landscape.

"We're pleased to welcome Sarah to our growing team and benefit from her hands-on experience across permitting, regulatory and environmental compliance within western Canada's mining ecosystem," noted Sean Roosen, chairman and chief executive officer.

About Osisko Development Corp.

Osisko Development 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-per-cent-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, a brownfield property with significant 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.