Osisko Development Announces Receipt of Final Permits for The Bonanza Ledge II Mine and Quesnel River Mill

MONTREAL, Oct. 27, 2021 - The Province of British Columbia, Lhtako Den? First Nation and Osisko Development Corp. ("Osisko Development" or the "Company") are pleased to announce the approval of amendments to Mines Act Permits M-238 and M-198 allowing for the expansion of the existing Bonanza Ledge II underground mine ("Bonanza Ledge II") with an increase in production from 150,000 t/yr to 215,000 t/yr. These amendments support the ongoing employment of 127 workers at the mine. The ore will be trucked from Bonanza Ledge II to the Quesnel River Mill ("QR Mill") for processing and tailings storage. The anticipated mine life of Bonanza Ledge II is approximately 18 months. The expansion of the Bonanza Ledge II project allows for continuity of mining while the Cariboo Gold project ("Cariboo Gold") Environmental Assessment proceeds. If approved, the Cariboo Gold project will extend mining by an additional 16 years and employ 459 people.

The Bonanza Ledge II deposit is located within the broader Cariboo Gold mining camp which is 100% owned by Barkerville Gold Mines Ltd., a wholly owned subsidiary of Osisko Development. Cariboo Gold is currently undergoing an Environmental Assessment under British Columbia's Environmental Assessment Act (2018) and is moving along according to timelines set under this new act. If the project is granted environmental assessment approval, it will provide employment, training and opportunities for meaningful economic partnerships for First Nations local communities and the Province of British Columbia. The project will be powered by hydro-electricity providing it with a sustainable source of low-carbon power.

Bruce Ralston, Minister of Energy, Mines and Low Carbon Innovation says, "I am pleased to see the Bonanza Ledge II project become a reality through a partnership between the Lhtako Den? Nation and Osisko Development Corp. This project promises to be a welcome opportunity for the surrounding communities and an example of industry working with First Nations to create meaningful partnerships while protecting our environment by harnessing the power of hydroelectricity to run their operation."

Chief Clifford Lebrun of the Lhtako Den? First Nation comments, "The Bonanza Ledge II project receipt of permits marks another milestone in what has turned out to be a very beneficial partnership between Lhtako Den? Nation and Osisko Development Corp. This partnership illustrates that First Nations and Industry can work together in a good way for the benefit of both partners, economically and with Community growth for Wells, Quesnel and the Lhtako Den? Nation. Its more than jobs and contract opportunities or training, it's the development and growth of all three communities and all the ones in between that is important here. The Lhtako Den? Nation looks forward to working together with Osisko Develoment Corporation in the future to move these values forward."

Sean Roosen, Chair and Chief Executive Officer of Osisko Development states, "The Bonanza Ledge II project is an important milestone for the growth of Osisko Development. This will provide hands on training and commissioning of our mining and processing complex at the Cariboo Gold Project as well as contributing important economic and social benefits for our partner First Nations and communities. Also receipt of these permits demonstrates the strong and efficient support of the province towards the safe, environmentally responsible and socially acceptable growth of British Columbia 's mining industry."

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 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, the outcome of the Environmental Assessment of the Cariboo Gold Projects and the expected timeline to receive such Environmental Assessment approval and the expected benefits of the Cariboo Gold project tp all stakeholders, the expected production from mining activities at the Bonanza Ledge II mine as well as the expected mine life thereof, 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.