 He represented Northumberland (1960–1974) and Baie-du-Vin (1974–1979) in the Legislative Assembly of New Brunswick, and was a provincial cabinet minister in New Brunswick in the 1960s.He was appointed to the Senate of Canada on March 26, 1979 on the advice of then-Prime Minister Pierre Elliott Trudeau, and served until his 75th birthday on February 16, 1996.His son Camille Thériault also served a member of the Legislative Assembly of New Brunswick, and was premier of New Brunswick from May 14, 1998 until June 21, 1999.