Osisko Development Corp. announced the results of an independent Feasibility Study prepared by BBA Engineering Ltd. in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101") for the Company's 100%-owned Cariboo Gold Project, located in central British Columbia. The FS outlines a robust and scalable phased development base case with low initial capital intensity of CAD 137.3 million and attractive operating costs for the underground development of the Cariboo Gold Project, producing approximately 1.87 million ounces ("Moz") of gold ("Au") over a 12-year mine life.

Initial production (Phase 1) in the first three years contemplates a 1,500 tonne per day ("tpd") operation from the Lowhee, Shaft and Mosquito deposits, yielding average annual production of 72,501 ounces. Concurrently, underground development will advance to ramp up operations to 4,900 tpd in year four, increasing average annual production to 193,798 ounces in Phase 2, with potential to scale production further in the future. Underground mining will be conducted using highly-mechanized, low-cost bulk tonnage methods designed to target the extraction of ore contained in gold vein corridors: a high-density network of mineralized quartz veins hosted mainly within unmineralized sandstone.

A pre-concentration ore sorting facility is expected to significantly improve processed grades by separating non-mineralized material from ore, while substantially reducing processing volumes, energy costs, and the overall environmental impact footprint of the operation with fewer tailings, reduced water usage and ability to use waste as backfill. The Company remains on track for completing the Environmental Assessment ("EA") process early in the second quarter of 2023 and anticipates receiving final permits by the end of 2023. FEASIBILITY STUDY HIGHLIGHTS: CAD 502 million after-tax net present value at a 5% discount rate ("NPV5%") (pre-tax CAD 691 million) at a base case gold price of USD 1,700 per ounce ("/oz") and CAD:USD exchange rate of 0.77; 20.7% after-tax internal rate or return ("IRR") (pre-tax 24.4%); CAD 79 million average annual after-tax free cash flow ("FCF"); CAD 901 million cumulative after-tax life-of-mine ("LOM") FCF; 163,695 ounces ("oz") of Au LOM average annual production; 72,501 oz Au Phase 1 (years 1 to 3) average annual production; 193,798 oz Au Phase 2 (years 4 to 12) average annual production; 1.87 Moz LOM total cumulative gold production; 3.78 grams per tonne ("g/t") Au average LOM diluted head grade: 4.43 g/t Au in Phase I (post-ore sorting 8.20 g/t Au); 3.72 g/t Au in Phase II (post-ore sorting 6.39 g/t Au); 92.0% average LOM recovery rate (93.6% in Phase I, 91.8% in Phase II); CAD 102.6 per tonne ("CAD /t") mined LOM total unit operating costs; Probable Mineral Reserves containing 16.7 million tonnes ("Mt") at an average grade of 3.78 g/t Au for a total of 2.03 Moz of gold; USD 792/oz Au LOM average cash costs; USD 968/oz LOM average all-in sustaining costs ("AISC"); CAD 137.3 million Phase 1 initial capital expenditures (including CAD 10.3 million in contingency costs); CAD 451.1 million Phase 2 expansion capital expenditures (including CAD 36.7 million in contingency costs); Peak full labour force (Phase 2) of 550 persons during operations and 635 during expansion construction.

The Cariboo Gold Project is an advanced stage gold exploration project 100%-owned by Osisko Development located in the historic Wells-Barkerville mining camp, in the District of Wells, central British Columbia, Canada. The total land package covers an area of 155,000 hectares and includes approximately 80 kilometers strike of mineral targets identified to date. FEASIBILITY STUDY DETAILS: The Cariboo Gold Project is an advanced stage gold exploration project 100%-owned by Osisko Development located in the historic Wells-Barkerville mining camp, in the District of Wells, central British Columbia, Canada.

The total land package covers an area of 155,000 hectares and includes approximately 80 kilometers strike of mineral targets identified to date.