Mr. Sean Roosen reports

OSISKO DEVELOPMENT COMMENCES SURFACE EXPLORATION DRILL CAMPAIGN ON COPPER-GOLD PORPHYRY TARGETS AT TINTIC PROJECT

Osisko Development Corp. has commenced an initial surface diamond drilling exploration campaign to test for copper-gold-molybdenum (Cu-Au-Mo) porphyry mineralization potential at the company's Big Hill target area, at its 100-per-cent-owned Tintic project, located in the historic East Tintic mining district in central Utah, United States. Following receipt of the required surface drill permits, the company mobilized a diamond drill rig from Major Drilling America of Salt Lake City, Utah, which arrived at site on Dec. 1, 2023, and commenced drilling activities.

Sean Roosen, chairman and chief executive officer of Osisko Development, commented: "With the surface drill permits in hand, we are very excited to start drilling high-priority targets on the Tintic property for copper-gold porphyry potential at depth. There was previously no detailed work completed using modern exploration techniques in these areas, and we expect the initial holes to provide us with invaluable information to support our understanding and interpretation of the entire Tintic district, and its potential to host a copper-gold porphyry centre."

Porphyry target drilling

• The Tintic district, located 65 kilometres (40 miles) from Rio Tinto's Bingham Canyon mine, has historically been recognized as an area prospective for porphyry-style copper-gold-molybdenum mineralization. Styles of mineralization and alteration present within the Tintic district support an interpretation of a classic porphyry-epithermal system with a high degree of rheologic and structural control on mineralization style and distribution.
• Two large lithocaps, presented as anomalous surface geochemical footprints -- a type of high heat signature indicative of potential significant subsurface volcanic activity -- have been identified within the company's Tintic project property, namely in the Big Hill and Silver Pass areas.
• An initial 3,000-metre (9,842 feet) of drilling in two holes comprises phase 1 of the surface diamond drilling program.
• The objective of this surface drilling program is to test priority targets for a potential porphyry-style copper-gold-molybdenum mineral system responsible for the significant high-grade gold and silver epithermal mineralization, and past-producing carbonate silver-lead-zinc replacement deposits on the Tintic property.
• Recall, as noted in the company's news release issued on Oct. 11, 2023, drilling of the Trixie West high-priority potential copper-gold-molybdenum porphyry target commenced in early October, 2023, from underground at the Trixie test mine. Approximately 70 per cent of the target drill hole has been completed to date and is nearing the projected target zone.

Regional exploration potential

The Tintic project is located within the historic Tintic mining district, a cluster of base and precious metal deposits covering greater than 200 square kilometres (approximately 80 square miles) within the East Tintic Mountains of north-central Utah. Commonly divided into Main, East, North and Southwest subdistricts, the greater Tintic district is collectively the second-largest metal-producing district in Utah following Bingham (Krahulec and Briggs, 2006).

Significant exploration potential exists for additional high-sulphidation Au-Ag (gold-silver) systems similar to Trixie, additional fissure zones adjacent to historic mines such as North Lily and Eureka Standard, historic carbonate replacement deposits (CRDs), including Burgin, North Lily and Tintic Standard, and deep copper-gold-molybdenum porphyry targets associated with known lithocaps such as Big Hill, Silver Pass and Government Canyon, which have been scarcely explored by previous operators.

Technical report

Information relating to the Tintic project and the current MRE (mineral resource estimate) for the Trixie deposit is supported by the technical report titled "NI 43-101 Technical Report, Initial Mineral Resource Estimate for the Trixie Deposit, Tintic Project, Utah, United States of America," dated Jan. 27, 2023 (with an effective date of Jan. 10, 2023), prepared for the company by independent representatives of Micon International Ltd. Reference should be made to the full text of the Tintic technical report, which was prepared in accordance with National Instrument 43-101 -- Standards of Disclosure for Mineral Projects and is available electronically on SEDAR+ and on EDGAR, under Osisko Development's issuer profile, and on the company's website.

A 3-D model and virtual site tour of Trixie and the wider Tintic project is accessible on-line.

Qualified persons

The scientific and technical information contained in this news release has been reviewed and approved by Maggie Layman, PGeo, vice-president of exploration for Osisko Development, and a qualified person within the meaning of National Instrument 43-101.

About Osisko Development Corp.

Osisko Development is a premier North American gold development company focused on high-quality past-producing properties located in mining-friendly jurisdictions with district-scale potential. The company's objective is to become an intermediate gold producer by advancing its 100-per-cent-owned Cariboo gold project, located in central British Columbia, Canada; the Tintic project in the historic East Tintic mining district in Utah, United States; and the San Antonio gold project in Sonora, Mexico. In addition to considerable brownfield exploration potential of these properties, that benefit from significant historical mining data, existing infrastructure and access to skilled labour, the company's project pipeline is complemented by other prospective exploration properties. The company's strategy is to develop attractive, long-life, socially and environmentally sustainable mining assets, while minimizing exposure to development risk and growing mineral resources.

We seek Safe Harbor.