Mr. Sean Roosen reports

OSISKO DEVELOPMENT REPORTS CONTRACTOR FATALITY AT THE CARIBOO GOLD PROJECT

On Jan. 22, 2026, a contractor working at surface suffered a fatal injury following an isolated incident at Osisko Development Corp.'s Cariboo gold project, located in central British Columbia, Canada.

The company promptly notified appropriate authorities, and an investigation of the incident is under way.

Sean Roosen, chairman and chief executive officer, stated: "We are deeply saddened by this tragic accident and extend our heartfelt condolences and support to our colleague's family, friends and coworkers during this difficult time. The health, safety and well-being of all employees and contractors working at the project is our highest priority."

Activities at the project have been temporarily suspended to allow for an investigation.

The company will provide further information in due course, as appropriate.

About Osisko Development Corp.

Osisko Development 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 producer by advancing its flagship permitted 100-per-cent-owned Cariboo gold project, located in central British Columbia, Canada. Its project pipeline is complemented by the Tintic project in the historic East Tintic mining district in Utah, United States -- 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 environmentally responsible mining assets while minimizing exposure to development risk and growing mineral resources.