In 1950 Bernier joined the teaching staff of College Mathieu in Gravelbourg, Saskatchewan, where he remained for over two years. During that time he also worked as the first program director of the localradio stationCFRG when it opened in June 1952. He left Gravelbourg in 1953 to become a producer of music programs for Canadian Broadcasting Corporation in Montreal. Working for the French-language side of the CBC, Bernier was particularly active with the CBC Radio program Premières during his first year with the organization. In 1954 he worked as a producer for the CBC Television programs Concerts pour la jeunesse and L'Heure du concert. He also produced several live programs of classical music, including performances of Igor Stravinsky's Histoire du soldat, Maurice Ravel's L'enfant et les sortilèges, Charles Gounod's Faust, Giacomo Puccini's Madama Butterfly, and Jules Massenet's Manon, among others. In 1956 Bernier was appointed music director of the Montreal Festivals, a post he remained in until 1960 when he became general director of the Orchestre Symphonique de Québec. In 1960 he conducted the orchestra in the world premiere of Roger Matton's Mouvement symphonique no. 1, and in 1963 he conducted them in the premiere of Serge Garant's Ouranos. After six years as general director, he succeeded Wilfrid Pelletier as the orchestra's principal conductor in 1966. He held that post for two years, during which time he championed contemporary works by Canadian and French composers, in particular those by Olivier Messiaen. He conducted the world premiere of Matton's Te Deum with the OSQ in 1967 and again for its European premiere in 1969 with the Office de Radiodiffusion Télévision Française. He also was a guest conductor with a number of French orchestras, including the Orchestre des Concerts Colonne and the Orchestre National Bordeaux Aquitaine. From 1959 to 1964 Bernier worked on the faculty of the Université Laval where he taught conducting and directed the university choir. He concurrently worked as the assistant director of the Conservatoire de musique du Québec à Québec from 1960 to 1968. From 1973 to 1975 he was President of the Canadian Music Council. He was also a member of the board of directors of the Encyclopedia of Music in Canada. He was appointed the first director of the Music Department at the University of Ottawa in 1969, a post he held through 1976. He remained on the UO's faculty until 1992. In 1977 he founded le Domaine Forget, a summer arts festival and school for music, dance, and theatre. He served as the general and artistic director of the school up until his death in Quebec City in 1993 at the age of 65.