His teaching and parish experience covered a number of years and were rewarding and successful.
His final position in education was principal of the École Normale Laval.
In 1867, he was appointed as the first Roman Catholic bishop of the diocese of Rimouski.
He served there for 24 years in an administration that was often stormy and difficult.
His last three years were marred by poor physical and mental health.
He resigned his duties in 1891 at the request of Cardinal Taschereau on behalf of papal authorities.His brother, Hector-Louis Langevin, was one of the Fathers of Confederation.