Osisko Development Corp. (TSX-V-ODV) is pleased to announce drilling results from the 2021 exploration and category conversion drill program campaign at its San Antonio Project in Sonora State, Mexico.

Summary

• A total of 177 holes and 27,900 meters were drilled in 2021. The objective of the drill program was to conduct exploration and resource drilling at a spacing of 25 meters and historic drilling validation for the three main target areas (Figure 1).
• This news releases encompasses all 5,563 meters from 27 holes at the California Target: CA-DD-21-020 to CA-DD-21-165 inclusive (Figure 2).
• The California gold mineralization is part of what is known as the El Realito Trend, located approximately 1 km to the southwest of Sapuchi and 4 km in length. The gold mineralization is typically pyrite with minor chalcopyrite and associated with hydrothermal breccia and quartzite, andesite and dacite intrusions.
• CA-DD-21-091 intersected 3.93 g/t Au over 13.50 meters including 26.50 g/t Au over 1.50 meters and is located 45 meters along strike within a sulphide zone from hole CA-DD-21-085 that assayed 0.92 g/t Au over 37.50 meters.
• Detailed drilling results are presented in Table 1, drill hole locations are presented in Table 2, and drill hole cross sections are presented in Figure 3.

Assay Highlights

• 0.63 g/t Au and 0.90 g/t Ag over 39.95 meters in hole CA-DD-21-026
• 1.50 g/t Au and 13.96 g/t Ag over 11.90 meters in hole CA-DD-21-037
• 1.73 g/t Au and 13.67 g/t Ag over 16.25 meters in hole CA-DD-21-051 including
• 12.85 g/t Au and 13.10 g/t Ag over 1.05 meters
• 1.62 g/t Au and 2.25 g/t Ag over 13.60 meters in hole CA-DD-21-064
• 1.28 g/t Au and 1.17 g/t Ag over 16.30 meters in hole CA-DD-21-070 including
• 8.21 g/t Au and 1.38 g/t Ag over 1.50 meters
• 0.92 g/t Au and 2.15 g/t Ag over 37.50 meters in hole CA-DD-21-085
• 0.87 g/t Au and 3.44 g/t Ag over 17.20 meters in hole CA-DD-21-085
• 1.56 g/t Au and 0.94 g/t Ag over 9.90 meters in hole CA-DD-21-091
• 3.93 g/t Au and 3.38 g/t Ag over 13.50 meters in hole CA-DD-21-091 including
• 26.50 g/t Au and 4.80 g/t Ag over 1.50 meters
• 0.73 g/t Au and 3.09 g/t Ag over 18.00 meters in hole CA-DD-21-100
• 2.41 g/t Au and 3.00 g/t Ag over 9.00 meters in hole CA-DD-21-100
• 0.76 g/t Au and 0.94 g/t Ag over 19.9 meters in hole CA-DD-21-113
• 2.82 g/t Au and 11.39 g/t Ag over 9.55 meters in hole CA-DD-21-116
• 21.00 g/t Au and 4.50 g/t Ag over 1.50 meters in hole CA-DD-21-0165

Sean Roosen, CEO of Osisko Development commented, “The California target is one of the three main zones at the San Antonio Project. These recent drill results at California show significant anomalous results in the oxide, transition and sulphide horizons and indicate continuity near surface and along strike and, open to the west along trend. These results increase our confidence in the upcoming San Antonio mineral resource estimate, which will be available in the near future. At least a dozen other target areas remain to be drill tested.”

The San Antonio Project gold mineralization is characterized by hydrothermal breccia that forms an approximately 3,000 m long east-northeast trending mineralization corridor with the Luz del Cobre copper deposit at the east. The gold mineralization is associated with intense sericite and chlorite alteration and is intrusion related with host sedimentary rocks. The breccia has been defined to a vertical depth of 500 meters and at an average depth of 250 meters. The upper 250 meters of the breccia is most altered and prospective. Drilling has occurred within the three major zones at Sapuchi, Golfo de Oro and California, over a combined strike length of 900 meters of the 3000 – meter trend.

True widths are estimated to be 80% to 100% of reported core length intervals. Intervals not recovered by drilling were assigned zero grade. Top cuts have not been applied to high grade assays. Complete assay highlights are presented in Table 1, drill hole locations are listed in Table 2.

Figure 1: San Antonio Mineral Zones overview map is available at:

https://www.globenewswire.com/NewsRoom/AttachmentNg/d34644d5-d3a4-436b-a104-4732989e2440

Figure 2: California Plan Map is available at:

https://www.globenewswire.com/NewsRoom/AttachmentNg/7afe75b3-f311-4e34-ba96-2934ac9fbcb4

Figure 3: California Section select drilling highlights is available at:

https://www.globenewswire.com/NewsRoom/AttachmentNg/a6421865-a2fe-4e8a-b429-42187bca10a4

Qualified Persons

Per National Instrument 43-101 Standards of Disclosure for Mineral Projects, Maggie Layman, P.Geo. Vice President Exploration of Osisko Development Corp., is a Qualified Person and has prepared, validated, and approved the technical and scientific content of this news release.

Quality Assurance – Quality Control

Once received from the drill and processed, all drill core samples are sawn in half, labelled and bagged. The remaining drill core is subsequently stored on site at a secured facility at the project site. Numbered security tags are applied to lab shipments for chain of custody requirements. Quality control samples are inserted at regular intervals in the sample stream, including blanks and reference materials with all sample shipments to monitor laboratory performance.

Drill core samples are submitted to ALS Geochemistry and Bureau Veritas preparation laboratory in Hermosillo and then sent to their analytical facilities in Vancouver, British Columbia for analysis. The facilities are accredited to the ISO/IEC 17025 standard for gold assays and all analytical methods include quality control materials at set frequencies with established data acceptance criteria. The entire sample is crushed, and 200 grams is pulverized. Analytical packages for ALS and BV are AA24 and FA450 respectively. Multi Element geochemistry is also analyzed with ME MS61 at ALS and MA 200 at BV.

About Osisko Development Corp.

Osisko Development Corp. is uniquely positioned as a premier gold development company in North America to advance the Cariboo Gold Project and other Canadian and Mexican properties, with the objective of becoming the next mid-tier gold producer. The Cariboo Gold Project, located in central British Columbia, is Osisko Development’s flagship asset with measured and indicated resources of 21.44 Mt at 4.6 Au g/t for a total of 3.2 million ounces of gold and inferred resource of 21.69 Mt at 3.9 Au g/t for a total of 2.7 million ounces of gold (see NI 43-101 Technical Report and mineral resource estimate effective October 5^th, 2020). The considerable exploration potential at depth and along strike distinguishes the Cariboo Gold Project relative to other development assets as does the historically low, all-in discovery costs of US $19 per ounce. The Cariboo Gold Project is advancing through permitting as a 4,750 tonnes per day underground operation with a feasibility study on track for completion in the first half of 2022. Osisko Development’s project pipeline is complemented by potential near-term production targeted from the San Antonio gold project, located in Sonora Mexico and early exploration stage properties including the Coulon Project and James Bay Properties located in Québec as well as the Guerrero Properties located in Mexico. Osisko Development began trading on the TSX Venture Exchange under the symbol “ODV” on December 2, 2020 and the Company’s 14,789,373 outstanding share purchase warrants were listed on the TSX Venture Exchange under the symbol “ODV.WT” on October 25, 2021.

Table 1: San Antonio Gold Project 2021 Length Weighted Drill Hole Gold and Silver Composites from California Zone

Table 2: Drill Hole Locations and Orientations