Independent Proxy Advisory Firm Institutional Shareholder Services Recommends Osisko Shareholders Vote for All Proposed Items at the Annual General Meeting

TORONTO, May 19, 2020 - Osisko Mining Inc. (“Osisko”) (TSX: OSK) is pleased to announce that Institutional Shareholder Services (“ISS”) has recommended that shareholders vote FOR all proposed items to be considered at its upcoming annual meeting of shareholders (“the Meeting”).

ISS is a prominent, third party proxy advisory firm who, among other services, provides proxy voting recommendations to pension funds, investment managers, mutual funds and other institutional shareholders. ISS made their recommendation that shareholders vote FOR all the proposed items at this year’s annual meeting of shareholders.

Osisko encourages shareholders to read the meeting materials in detail. Copies of the meeting material is available under Osisko’s profile on SEDAR at www.sedar.com and on Osisko's website at http://www.osiskomining.com

YOUR VOTE IS IMPORTANT - PLEASE VOTE TODAY

The Osisko Board of Directors UNANIMOUSLY recommends that Shareholders

Vote IN FAVOUR of All the Proposed Items.

Submit your vote well in advance of the proxy voting deadline at 10:00 a.m. Toronto time on Wednesday May 27, 2020

Shareholders are encouraged to vote using the internet or telephone, to ensure your vote is received in a timely manner.

Registered shareholders may vote by: Shares held in own name and represented by a physical certificate

• Internet: www.voteproxyonline.com
• Facsimile: 416-595-9593

Beneficial shareholders (shares held with a broker, bank or other intermediary) may vote by:

• Following the instructions on your voting instruction forms

Osisko Meeting

The Meeting is scheduled for 10:00 a.m. (Toronto Time) on Friday, May 29, 2020. Join us via Teleconference. Dial 1-855-342-6455 (North America Toll Free) or 1-416-933-3853 (Outside North America). Conference ID 2526184. Participants should dial in 5-10 minutes prior to the scheduled start time of the meeting.

Shareholder Questions and Assistance

If you have any questions or require assistance voting your Osisko shares, please contact our proxy solicitation agent, Laurel Hill Advisory Group, at 1-877-452-7184 toll-free in North America, or call collect outside North America at +1 416 304-0211, or by e-mail at assistance@laurelhill.com

About Osisko Mining Inc.

Osisko is a mineral exploration company focused on the acquisition, exploration, and development of precious metal resource properties in Qu?bec, Canada. Osisko holds a 100% interest in the high-grade Windfall gold deposit located between Val d’Or and Chibougamau and has a 100% undivided interest in a large area of claims in the surrounding Urban Barry area and nearby Qu?villon area (over 2,700 square kilometres).