In doing so, they became the sixth NHL team in seven weeks to make a coaching change.
Therrien is the second straight coach of the league's most storied franchise to leave without posting a winning record.
Julien, 42, was in his third season with Hamilton of the American Hockey League. The Bulldogs had a league-best 33-6-3-3 record, and are on pace to break that team's 67-year-old mark for wins and points.
Julien leaves the team in the midst of a 25-game points streak (21
The 39-year-old Therrien was named the 25th Canadiens coach on Nov. 20, 2000, and led Montreal to an upset of the top-seeded Boston Bruins in the Eastern Conference quarterfinals last year. The Canadiens had tied a franchise record by missing the playoffs the three previous seasons.
In his brief stint with the club, Therrien compiled a 77-77-13-13 record.
Vezina and Hart Trophy winner Jose Theodore struggled early this season, but improved in December, and Montreal was a season-high four games over .500 (16-12-4-2) on Dec. 21. However, the Canadiens are 2-7-1-2 in their last 12 games, and are tied for ninth in the Eastern Conference.
Therrien replaced Alain Vigneault, who finished with a 109-122-35 record to become the first Canadiens coach without a winning record since Alfred "Pit" Lepine went 10-33-5 in 1939-40.
Montreal is the second team to name a coach this week. On Tuesday, the Atlanta Thrashers named Bob Hartley to replace interim coach and General Manager Don Waddell. Hartley was fired by the Colorado Avalanche on Dec. 18.
Jessica Simpson shares three-way kiss with friends in photo
Teacher apologizes for showing sexual image of herself in class