Osisko Development Corp. — Capital/Financing Update 2025

Dec 23, 2025

CONSENT OF EXPERT

TO: Autorité des marchés financiers
Ontario Securities Commission
British Columbia Securities Commission
Alberta Securities Commission
Financial and Consumer Affairs Authority of Saskatchewan
Manitoba Securities Commission
Financial and Consumer Services Commission, New Brunswick
Nova Scotia Securities Commission
Office of the Superintendent of Securities, Prince Edward Island
Office of the Superintendent of Securities Service, Newfoundland and Labrador
Office of the Superintendent of Securities, Northwest Territories
Office of the Superintendent of Securities, Nunavut
Office of the Superintendent of Securities, Yukon

Dear Sirs/Mesdames,

Re: Osisko Development Corp. (the "Corporation")
Base Shelf Prospectus of the Corporation dated December 23, 2025 (the "Prospectus")

In connection with the filing of the Prospectus, I hereby consent to being named in the Prospectus in connection with my involvement in the preparation of the technical report titled "NI 43-101 Technical Report, Feasibility Study for the Cariboo Gold Project, District of Wells, British Columbia, Canada" dated June 11, 2025 with an effective date of April 25, 2025 (the "Technical Report"), and to the use of the Technical Report, or any portion thereof, and to the inclusion or incorporation by reference of information derived from the Technical Report in the Prospectus.

I have read the Prospectus and have no reason to believe that there are any misrepresentations in the information contained in it that are derived from the Technical Report or within my knowledge as a result of the services performed by me in connection with the Technical Report.

DATED this 23rd day of December, 2025.

(signed) "Jean-François Maillé"

Jean-François Maillé, P.Eng
JDS Energy & Mining Inc.