Christian Lepine takes over from Jean-Claude Cardinal Turcotte, who held the post for 22 years at Canada's second-largest diocese.
Turcotte offered his resignation last year after his 75th birthday, the mandatory age of retirement according to church rules.
While accepting Turcotte's resignation, the Pope also announced that Turcotte will remain administrator of the diocese until the new archbishop takes over.
Turcotte is known for his affable disposition and media savvy. He is also known for having taken a public stand against abortion, famously returning his Order of Canada after pro-choice activist Henry Morgentaler was named to the order in 2008.
Lepine was ordained in 1983, was a pastor at various Montreal-area churches and spent two years at the Vatican. He was named auxiliary bishop last year.
The Canadian Conference of Catholic Bishops and the Archdiocese of Montreal both made announcements this morning confirming the appointment.