Gratien Gélinas was born in Saint-Tite-de-Champlain, Quebec, on December 8, 1909. His parents were Mathias Gélinas and Genèva Davidson. He did his classical studies first with the Pères du Saint-Sacrement in Terrebonne in 1923, then at the Collège de Montréal from 1924 to 1928.
After his studies, Gélinas worked as a salesman in the well-known store Dupuis Frères in Montreal, and as an accountant for the insurance company La Sauvegarde. In 1931, he took evening classes at the École des hautes études commerciales and obtained a degree in accounting in 1934.
Gratien Gélinas married Simone Lalonde in 1935 and had six children. She died from an illness in 1967. In 1973, he married actress Huguette Oligny.
Gélinas earned honorary degrees from eleven Canadian universities. In 1949, the Université de Montréal presented him with the first honorary doctorate granted to a person from the theatre in Canada. During his career, he received many prices and honours including the Best Canadian Film Award for Tit-Coq (1953) and the Médaille de l'Académie canadienne-française in recognition for his work (1988). He was made a member of the Ordre national du Québec (1985) and a Companion of the Order of Canada (1989).