Osisko Development Reports Underground Sampling Results

79.45 oz/t Au and 6.27 oz/t Ag over 5.5 ft. including 434.09 oz/t Au and 33.65 oz/t Ag over 1.0 ft.

(2,724 g/t Au and 215.12 g/t Ag over 1.68 m including 14,883.2 g/t Au and 1,153 g/t Ag over 0.30 m.)

MONTREAL, July 7, 2022 – Osisko Development Corp. (“Osisko Development” or the “Company” - https://www.commodity-tv.com/ondemand/companies/profil/osisko-development-corp/) is pleased to announce results from its ongoing underground exploration program on the recently acquired Tintic project and its 100% owned Trixie Mine (“Trixie”), as well as mineral claims covering more than 17,000 acres (including over 14,200 acres of which are patented) located in Central Utah’s historic Tintic Mining District (together with Trixie, the “Tintic Project”).

Summary

-          Trixie is one of several gold and base metal targets within the larger Tintic Project. The discovery of the T2 and T4 mineralized structures at Trixie in late 2020 by Tintic Consolidated Metals, LLC (“TCM”) showed gold (“Au”) and silver (“Ag”) grades associated with high sulphidation alteration hosted within quartzites that are capped by impermeable shales and volcanics.

-          Current underground mining activities at Trixie are directed by the exploration sampling and drilling results.

-          Results shown below are derived from 703 samples collected across a total of 183 sites (site ID 783 to 934) near the 625 ft level at Trixie across a total combined strike length of 650 ft. (~200 m). See Figure 1.

-          The sample results indicate anomalous gold results throughout the entire sampled area, and along exploration cross-cuts (Figure 1).

-          The mineralized structures remain open along strike and at depth and significant potential exists to expand the known mineralization.

-          The Company is currently expanding underground developments and utilizing one underground diamond drill rig and one surface reverse circulation rig to aid in the delineation of an initial mineral resource estimate by the end of Q4 2022. Results from this drilling program are pending.

Assay Highlights

A length weighted composite for each face Site ID is shown in Table 1 and individual higher grade samples are also identified within the composite. Samples are collected in feet and assays are reported in g/t Au. Conversions to metric and imperial are rounded to two decimal places.

Chris Lodder, President of Osisko Development commented, “The Trixie underground sampling results from 2020 to present show exceptional continuity of high grades associated with the T2 structure. These 2022 samples along with the historic sampling by TCM, and in combination with the ongoing exploration developments within the present 720 ft strike by 175 ft vertical by 80 ft wide zone gives Osisko Development with a strong base for present mining activity and initial resources estimation. We will continue to use the present shaft / hoist at Trixie but we anticipate to increase access and mining capacity to the 625 ft and lower levels of Trixie through a new underground ramp initiated very recently and expected to reach the 625 ft level in Q1 2023.”

The T2 and T4 mineralized structures are associated with high-sulphidation epithermal mineralization,  structurally controlled and hosted within the brittle Tintic Quartzite and capped by the impermeable shales of the Lower Ophir Formation. The T2 structure is 1 to 8 ft. wide (0.3 m to 2.4m) and mineralization consists of native Au, and rare Au-Ag – rich telluride minerals with quartz. The T4 is a mineralized stockwork zone ranging from to 10 to 80 ft. (3 m to 25 m) and 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 currently defined over 220 meters (720 feet) in strike and reports consistent multi-ounce gold grades along its entire strike length.

Face Sampling Methodology

As most structures at Trixie are steeply dipping to the east or west, current sampling procedures are designed to sample the structure. Channel samples are collected and do not exceed 3 ft. (1.0 m) in length. The face is washed for safety, and for better identification of mineralization, alteration and structures. The hangingwall and footwall of the structures are marked up on the face and back, samples intervals are marked up and follow lithological contacts.

For further information on Tintic, including additional production details please see the technical report on the Tintic Project, entitled "Technical Report on the Tintic Project, East Tintic Mining District, Utah County, Utah, USA", dated June 10, 2022 (effective date of June 7, 2022), and filed at www.sedar.com under the profile of the Company.

Figure 1: 625 L Map with Select Assay Highlights

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 (QA)/Quality Control (QC)

All underground face samples are collected by TCM geologists from each of the active mining faces, with samples transported by the geologists from Trixie to the on-site TCM laboratory located at the Burgin administrative complex. Underground samples are dried, crushed to <10 mm and a 250 g split is taken. The split is pulverized, and a 30 g Fire Assay with gravimetric finish is completed to determine gold and silver grades, reported in oz./short ton and g/t.

The TCM Burgin laboratory is not a certified analytical laboratory, but the facility is managed by a qualified Laboratory Manager with annual auditing by technical staff. Inter-laboratory check assays using ALS Laboratory as a third-party independent analysis of samples is routinely carried out as part of ongoing QA/QC work. Certified OREAS Quality Control (“QC”) standards and blanks are inserted at regular intervals in the sample stream to monitor laboratory performance.

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 Datashed 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 assay include gold and silver by fire assay of 50g 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 TCM and coarse rejects are disposed after 90 days. Assays are reported to TCM, and then loaded into Datashed, QA/QC samples are checked, and assays merged with sample information for future reporting.

Cautionary Statements

The Company cautions that the decision to commence production at Trixie in the form of small scale underground mining and batch vat leaching has been made without the benefit of a feasibility study, or reported mineral resources or mineral reserves, demonstrating economic and technical viability, and, as a result there may be increased uncertainty of achieving any particular level of recovery of material or the cost of such recovery. The Company cautions that historically, such projects have a much higher risk of economic and technical failure. There is no guarantee that production will continue as anticipated or at all or that anticipated production costs will be achieved. The failure to continue production may have a material adverse impact on the Company's ability to generate revenue and cash flow to fund operations. Failure to achieve the anticipated production costs may have a material adverse impact on the Company's cash flow and potential profitability. In continuing current operations at Trixie after closing, the Company will not be basing its decision to continue such operations on a feasibility study, or reported mineral resources or mineral reserves demonstrating economic and technical viability. The Company cautions that mining at Trixie could be suspended at any time.

The Company is subject to the reporting requirements of the applicable Canadian securities laws, and as a result reports information regarding mineral properties, mineralization and estimates of mineral reserves and mineral resources, including the information in the Tintic Technical Report and this news release, in accordance with Canadian reporting requirements, which are governed by NI 43-101. As such, such information concerning mineral properties, mineralization and estimates of mineral reserves and mineral resources, including the information in the Tintic Technical Report and this news release, is not comparable to similar information made public by U.S. companies subject to the reporting and disclosure requirements of the SEC.

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, U.S.A. and Mexican properties, with the objective of becoming the next mid-tier gold producer. The Cariboo Gold Project, located in central British Columbia, Canada, is Osisko Development's flagship asset. The considerable exploration potential at depth and along strike distinguishes the Cariboo Gold Project relative to other development assets. Osisko Development's project pipeline is complemented by its interest in the San Antonio gold project, located in Sonora, Mexico and the Trixie gold test mine, located in Utah, U.S.A.

For further information about Osisko Development [(NYSE: ODV; TSX-V:ODV)], please visit www.osiskodevelopment.com or follow us on Twitter @OsiskoDev

Investor Contact:

Jean Francois Lemonde

VP, Investor Relations

[email protected]

Tel: 514-299-4926

In Europe:

Swiss Resource Capital AG

Jochen Staiger

[email protected]

www.resource-capital.ch

Forward-looking Statements

Certain statements contained in this news release may be deemed "forward-looking statements" within the meaning of the United States Private Securities Litigation Reform Act of 1995 and "forward-looking information" within the meaning of applicable Canadian securities legislation. These forward‐looking statements, by their nature, require Osisko Development to make certain assumptions and necessarily involve known and unknown risks and uncertainties that could cause actual results to differ materially from those expressed or implied in these forward‐looking statements. Forward‐looking statements are not guarantees of performance. Words such as "may", "will", "would", "could", "expect", "believe", "plan", "anticipate", "intend", "estimate", "continue", or the negative or comparable terminology, as well as terms usually used in the future and the conditional, are intended to identify forward‐looking statements. Information contained in forward‐looking statements is based upon certain material assumptions that were applied in drawing a conclusion or making a forecast or projection, including management's perceptions of historical trends, current conditions and expected future developments, results of further exploration work to define and expand mineral resources, and that the deposit remains open for expansion at depth and down plunge, as well as other considerations that are believed to be appropriate in the circumstances, and any other information herein that is not a historical fact may be "forward looking information". Material assumptions also include, management's perceptions of historical trends, current conditions and expected future developments, results of further exploration work to define or expand any mineral resources, the ability to continue production at its Trixie mine, as well as other considerations that are believed to be appropriate in the circumstances. Osisko Development considers its assumptions to be reasonable based on information currently available, but cautions the reader that their assumptions regarding future events, many of which are beyond the control of Osisko Development, may ultimately prove to be incorrect since they are subject to risks and uncertainties that affect Osisko Development and its business. Such risks and uncertainties include, among others, risks relating to capital market conditions, the ability to continue current production, regulatory framework, the ability of exploration activities (including drill results) to accurately predict mineralization; errors in management's geological modelling; the ability of to complete further exploration activities, including drilling; property and stream interests in the Project; the ability of the Company to obtain required approvals; the results of exploration activities; risks relating to exploration, development and mining activities; the global economic climate; metal prices; dilution; environmental risks; and community and non-governmental actions and the responses of relevant governments to the COVID-19 outbreak and the effectiveness of such responses. Readers are urged to consult the disclosure provided under the heading "Risk Factors" in the Company's annual information form for the year ended December 31, 2021, as amended, which has been filed on SEDAR (www.sedar.com) under Osisko Development's issuer profile and on the SEC's EDGAR website (www.sec.gov), for further information regarding the risks and other factors applicable to the exploration results. Although the Company's believes the expectations conveyed by the forward-looking statements are reasonable based on information available at the date of preparation, no assurances can be given as to future results, levels of activity and achievements. The Company disclaims any obligation to update any forward-looking statements, whether as a result of new information, future events or results or otherwise, except as required by law. There can be no assurance that these forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this news release. No stock exchange, securities commission or other regulatory authority has approved or disapproved the information contained herein.

Table 1: 2022 Length Weighted Assay Composites at Trixie