He ran for the Ontario legislature in the 1963 provincial election, and lost to Liberal-Labour candidate Robert Gibson by 840 votes in Kenora. Gibson died in 1966, and Bernier was elected in a by-election to replace him. He was returned by an increased margin in the 1967 provincial election, and served as a backbench supporter of the John Robarts administration. When Bill Davis succeeded Roberts as premier on March 1, 1971, he appointed Bernier as his Minister of Mines and Northern Affairs.