 On June 22, 1939, Charbonneau was appointed Bishop of Hearst by Pope Pius XI.He received his episcopal consecration on the following August 15 from Archbishop Joseph-Guillaume-Laurent Forbes, with Archbishop Emile Yelle, PSS, and Bishop Louis Rhéaume, OMI, serving as co-consecrators.Charbonneau was later named Coadjutor Archbishop of Montreal and Titular Archbishop of Amorium on May 21, 1940.