Mr. John Burzynski reports

OSISKO ANNOUNCES HYDROELECTRIC POWER ALLOCATION FOR WINDFALL

Windfall Mining Group (Osisko Mining Inc.'s 50-per-cent jointly owned partnership with a Gold Fields Ltd. subsidiary) has concluded the hydro-electricity power allocation agreement with Hydro-Quebec, a wholly owned Crown corporation of the Quebec government.

The forecasted power demand and allocation for the electrical installation is 27,400 kilowatts for Windfall. Power will be delivered at the MICO substation located in nearby Waswanipi, Que., then be transported using a dedicated power line (currently under construction) from the MICO substation to Windfall by Miyuukaa Corp. (please see news release of Osisko dated March 16, 2023).

John Burzynski, chairman and chief executive officer, commented: "Receipt of the Windfall power allocation is a major milestone, as it will significantly reduce greenhouse gas emissions and project power costs. It is well aligned with our joint venture ESG goals."

Power line construction work is progressing on schedule with the hook up date anticipated in early 2024.

About the Windfall gold deposit

The Windfall gold deposit is located between Val d'Or and Chibougamau in the Abitibi region of Quebec, Canada. The mineral resource estimate on Windfall (with an effective date of June 7, 2022) and the mineral reserve estimate on Windfall (with an effective date of Sept. 1, 2022) are described in the technical report entitled "Feasibility Study for the Windfall Project, Eeyou Istchee James Bay, Quebec, Canada," and dated Jan. 10, 2023 (with an effective date of Nov. 28, 2022). The Windfall resource estimate, assuming a cut-off grade of 3.50 grams per tonne gold, comprises 811,000 tonnes at 11.4 g/t Au (297,000 ounces) in the measured mineral resource category, 10.25 million tonnes at 11.4 g/t Au (3,754,000 ounces) in the indicated mineral resource category and 12,287,000 tonnes at 8.4 g/t Au (3,337,000 ounces) in the inferred mineral resource category. The Windfall reserve estimate, assuming a 3.5 g/t operating, 2.5 g/t incremental and 1.7 g/t development cut-off grade, comprises 12,183,000 tonnes at 8.06 g/t Au (3,159,000 ounces) in the probable mineral reserves category. The key assumptions, limitations and methods used in the FS technical report, including the related Windfall resource estimate and Windfall reserve estimate, are described in the FS technical report, which was prepared in accordance with National Instrument 43-101 (Standards of Disclosure for Mineral Projects). The FS technical report is available on SEDAR under Osisko Mining's issuer profile. The Windfall gold deposit is currently one of the highest-grade resource-stage gold projects in Canada and has world-class scale. Mineralization occurs in three principal areas: Lynx, Main and Underdog. Mineralization is generally composed of subvertical lenses following intrusive porphyry contacts plunging to the northeast. The resources are defined from surface to a depth of 1,600 metres, including the Triple 8 (TP8) zone. The reserves are defined from surface to a depth of 1,100 metres. The deposit remains open along strike and at depth. Mineralization has been identified at surface in some areas and as deep as 2,625 metres in others with significant potential to extend mineralization down plunge and at depth.

Qualified person

The scientific and technical content in this news release has been reviewed and approved by Mathieu Savard, PGeo (OGQ No. 510), president of Osisko Mining, who is a qualified person (within the meaning of National Instrument 43-101).

About Osisko Mining Inc.

Osisko Mining is a mineral exploration company focused on the acquisition, exploration and development of precious metal resource properties in Canada. Osisko Mining holds a 50-per-cent interest in the high-grade Windfall gold deposit located between Val d'Or and Chibougamau in Quebec, and holds a 50-per-cent interest in a large area of claims in the surrounding Urban Barry area and nearby Quevillon area (over 2,300 square kilometres).

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