Osisko Development Corp. (TSX-V: ODV) (NYSE: ODV) is pleased to announce underground diamond drilling results as part of its ongoing exploration program at its 100%-owned Trixie test mine, within the Company’s wider Tintic Project, located in the historic East Tintic Mining District in central Utah, U.S.A.

Chris Lodder, President of Osisko Development, commented, “These drill results from the 2022 underground diamond drilling campaign continue to showcase the continuity of the high-grade mineralization within the T2 structure and wider zones of mineralization within the T4 stockwork zone. Our current underground drill program is building upon these results and this work is expected to support a future update to the existing Trixie mineral resource estimate.”

DRILL ASSAY HIGHLIGHTS

This news release includes assays from 8 DD holes (refer to Table 1). Select assay highlights include:

• 128.50 grams per tonne gold and 220.00 g/t silver over 0.52 meters in hole TUG-625-034 (3.75 troy ounces per short ton Au and 6.42 oz/t Ag over 1.70 feet
• 17.63 g/t Au and 175.81 g/t Ag over 3.96 m in hole TUG-625-034 (0.51 oz/t Au and 5.13 oz/t Ag over 13.00 ft.)
• 7.51 g/t Au and 50.19 g/t Ag over 5.79 m in hole TUG-625-034 (0.22 oz/t Au and 1.46 oz/t Ag over 19.00 ft.)
• 36.81 g/t Au and 30.89 g/t Ag over 3.35 m in hole TUG-625-036 (1.07 oz/t Au and 0.90 oz/t Ag over 11.00 ft.) including
  • 134.50 g/t Au and 65.00 g/t Ag over 0.61 m (3.92 oz/t Au and 1.90 oz/t Ag over 2.00 ft.)
• 20.88 g/t Au and 45.08 g/t Ag over 5.64 m in hole TUG-625-037 (0.61 oz/t Au and 1.31 oz/t Ag over 18.50 ft.) including
  • 154.00 g/t Au and 397.00 g/t Ag over 0.46 m (4.49 oz/t Au and 11.58 oz/t Ag over 1.50 ft.)
• 53.27 g/t Au and 90.24 g/t Ag over 2.44 m in hole TUG-625-037 (1.55 oz/t Au and 2.63 oz/t Ag over 8.00 ft.) including
  • 105.50 g/t Au and 177.00 g/t Ag over 0.91 m (3.08 oz/t Au and 5.16 oz/t Ag over 3.00 ft.)
• 84.40 g/t Au and 301.00 g/t Ag over 0.73 m in hole TUG-625-085 (2.46 oz/t Au and 8.78 oz/t Ag over 2.40 ft.)
• 15.61 g/t Au and 163.56 g/t Ag over 2.44 m in hole TUG-625-085 (0.46 oz/t Au and 4.77 oz/t Ag over 8.00 ft.)
• 10.78 g/t Au and 38.15 g/t Ag over 3.96 m in hole TUG-625-094 (0.31 oz/t Au and 1.11 oz/t Ag over 13.0 ft.)
• 57.50 g/t Au and 246.00 g/t Ag over 0.76 m in hole TUG-625-094 (1.68 oz/t Au and 7.18 oz/t Ag over 2.50 ft.)
• 78.80 g/t Au and 106.00 g/t Ag over 0.64 m in hole TUG-625-100 (2.30 oz/t Au and 3.09 oz/t Ag over 2.10 ft.)
• 42.10 g/t Au and 69.90 g/t Ag over 1.37 m in hole TUG-625-100 (1.23 oz/t Au and 2.04 oz/t Ag over 4.50 ft.)
• 16.86 g/t Au and 60.26 g/t Ag over 4.54 m in hole TUG-625-100 (0.49 oz/t Au and 1.76 oz/t Ag over 14.90 ft.)
• 30.80 g/t Au and 114.00 g/t Ag over 2.26 m in hole TUG-625-100 (0.90 oz/t Au and 3.33 oz/t Ag over 7.40 ft.)

DRILL SUMMARY

• The high-grade intercepts disclosed in this news release are located within the T2 structure and T4 stockwork in the central and southern areas of the current Trixie Mineral Resource Estimate (see Figure 2). These drilling results will provide valuable infill data in order to improve our understanding and the confidence level of the mineralized zones defined in the Trixie MRE.
• The T2 structure continues to intersect high-grade mineralization including 53.27 g/t Au and 90.24 g/t Ag over 2.44 m in hole TUG-625-037 and 30.80 g/t Au and 114.00 g/t Ag over 2.26 m in hole TUG-625-100 (see Figure 3).
• The T4 stockwork zone returned several anomalous intervals, displaying both high-grade structures analogous to the T2 structure and wider mineralized zones as seen in hole TUG-625-037 that intersected 20.88 g/t Au and 45.08 g/t Ag over 5.64 m and 42.00 g/t Au and 60.40 g/t Ag over 0.76 m (including 154.00 g/t Au and 397.00 g/t Ag over 0.46 m).

EXPLORATION NEXT STEPS

• The Company currently has two underground diamond drill rigs in operation at Trixie conducting exploration activities.
• Follow up exploration targets include drill testing of the contact beneath the Ophir Shale cap rock, where mineralization appears to be concentrated, as well as testing the 75-85 structure at depth.
• In 2022, the Company completed 28 surface reverse circulation drill holes near Trixie totalling approximately 8,753 m (28,718 ft.) and 66 underground DD holes in the 625 level at Trixie totalling approximately 2,985 m (9,796 ft.). To date, assays have been received for 8 RC drill holes and 64 DD holes.

About Trixie

The Trixie test mine is one of several gold and base metal targets within the larger Tintic Project consisting of >17,000 acres of patented mining claims and mineral leases within the historic East Tintic Mining District of Central Utah, U.S.A. The T2 and T4 structures at Trixie show multi-ounce gold grades associated with high sulphidation epithermal mineralization, structurally controlled and hosted within quartzites. The T2 structure mineralization consists of native Au, and rare Au-Ag – rich telluride minerals with quartz. The T4 is a mineralized stockwork zone is located in the hanging wall of the T2 and is comprised of Au-Ag rich mineralization in host rock quartzite with quartz-barite-sulphosalt stockwork veining. Mineralization reports consistent multi-ounce gold grades along the entire strike length.

Information relating to the Tintic Project and the Trixie MRE 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 January 27, 2023 (with an effective date of January 10, 2023) prepared for the Company by independent representatives of Micon International Limited (the “Tintic Technical Report“). 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 (“NI 43-101“) and is available electronically on SEDAR (www.sedar.com) and on EDGAR (www.sec.gov) under Osisko Development’s issuer profile and on the Company’s website at www.osiskodev.com.

Figure 1: Trixie Project Area

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Figure 2: Drill Plan Map

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Figure 3: Cross Section of Underground Drilling at 625 L at Trixie

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Table 1: Drilling Length Weighted Assay Composites at Trixie

Qualified Persons

The scientific and technical information contained in this news release has been reviewed and approved by Maggie Layman, P.Geo., Vice President, Exploration of Osisko Development, and a “qualified person” within the meaning of NI 43-101.

Quality Assurance– Quality Control

True width determination is estimated to be approximately 0.3 m to 2.4 m (1 to 8 ft.) wide for the T2 structure and approximately 3 m to 25 m (10 to 80 ft.) for the T4 mineralized stockwork zone located in the hanging wall of the T2 structure. All drill core and exploration samples are dispatched to ALS Laboratory for offsite sample preparation and analysis. Samples are assigned a unique sample ID. All geological and sampling information is entered into Datamine Fusion database. Core is sawn in half and half are sampled. Certified standards and blanks inserted into all sample dispatches. Samples are collected by Old Dominion Transportation and dispatched to ALS Laboratory in Reno, NV. Sample submission forms accompany the samples, and digital copies emailed to ALS.

All sample preparation is completed by ALS, including crushing and pulverizing (Prep31) of samples. Analytical assays include gold and silver by fire assay of 50 g sample with AAS finish (Au-AA26), over limits by gravimetric analysis (Au-Grav22). Multi element analysis is by four acid digest (ME-MS61). The pulps are returned to Osisko Development and coarse rejects are disposed after 90 days. Assays are reported to Osisko Development, and then loaded into Datamine Fusion, QA/QC samples are checked, and assays merged with sample information for future reporting.

About Osisko Development Corp.

Osisko Development Corp. 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%-owned Cariboo Gold Project, located in central BC, Canada, the Tintic Project in the historic East Tintic mining district in Utah, U.S.A., 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.