[citation needed] Desmarais began his career with S.G. Warburg & Co. in London, England, and with Standard Brands Incorporated in New York.
[3][4] On February 13, 2020, Desmarais retired from the functions of co-CEO and as of 2021[update] continued to play an active role in the governance of Power Corporation as chairman of its board of directors.
[2] Desmarais is involved with Centraide of Greater Montréal; he founded the Major Donors Circle in 1997 and had been its Honorary Chairman for many years, until 2017.
[11] He received the 2018 Michèle Thibodeau-DeGuire Award and became the first Governor Emeritus for his contribution and support in the fight against poverty and social exclusion.
[13] In 2014 Desmarais participated in a ski expedition to the North Magnetic Pole, organized by True Patriot Love, Canada's largest charity supporting military families.
The national campaign raised more than $500 million and protected 752,000 acres (300,000 hectares) of at-risk natural habitat across Canada, home to more than 145 species at risk.