Osisko Development Appoints Martin Ménard as Vice-President, Engineering and Construction and Announces Grant of Stock Options and RSUs to Officers

MONTREAL, Aug. 16, 2021 - Osisko Development Corp. ("Osisko Development" or the "Company") is pleased to announce the appointment of Mr. Martin M?nard as Vice-President, Engineering and Construction.

Mr. M?nard brings fifteen years of experience in various engineering and management roles on energy, mining and mineral processing projects worldwide, including most recently as Chief Operating Officer at AEX Gold Inc. He has held leading technical & managerial roles, notably for Newmont Mining on their Merian Project in Suriname and IAMGOLD on their Essakane project in Burkina Faso. He earned a Master's of Science degree in Economics from the Universitat Pompeu Fabra and a Bachelor degree in Electrical Engineering from the McGill University.

The Company also announces that incentive stock options have been granted to officers to purchase 103,900 common shares at a price of $5.63 for five years with vesting terms of one third of the total grant at each of the first three anniversaries of such grant. These options have been granted in accordance with the Company's Stock Option Plan. The Company has also granted an aggregate total of 78,700 restricted share units ("RSUs") to officers in accordance with the RSU Plan of the Company. The RSUs are subject to the following vest terms: one half (1/2) is time-based and vests on the third anniversary of such grant while the remaining half (1/2) , which also vests on the third anniversary of such grant, is subject to the achievement of approved long-term objectives over a three-year period.

About Osisko Development Corp.

Osisko Development Corp. is well-capitalized and 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 for resource 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 Qu?bec 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.

Forward-looking Statements

Certain statements contained in this press release may be deemed "forward‐looking statements" within the meaning of applicable Canadian and U.S. securities laws. 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, including with respect to the development and exploration potential of the Cariboo Gold Project and other Canadian and Mexican properties, Osisko Development becoming the next mid-tier gold producer and the timely completion and outcome of the Cariboo Gold Project feasibility study, 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 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 royalty interests in the Cariboo gold deposit; the ability of the Corporation to obtain required approvals; the results of exploration activities; risks relating to 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.

For additional information with respect to these and other factors and assumptions underlying the forward‐looking statements made in this news release concerning Osisko Development, see the Filing Statement available electronically on SEDAR (www.sedar.com) under Osisko Development's issuer profile. The forward‐looking statements set forth herein concerning Osisko Development reflect management's expectations as at the date of this news release and are subject to change after such date. Osisko Development disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, other than as required by law.

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.