He had previously served as head coach of the New Jersey Devils in the NHL, as well as in the American Hockey League (AHL) with the Hamilton Bulldogs.
[2] Before playing in the NHL, Julien spent six years in the Ontario Hockey League (OHL) with the Oshawa Generals and Windsor Spitfires.
Additionally, he has also played in the Central Hockey League (CHL) for the Salt Lake Golden Eagles; in the International Hockey League (IHL) for the Kansas City Blades and the Milwaukee Admirals; and in the AHL for the Fredericton Express, Baltimore Skipjacks, Halifax Citadels and Moncton Hawks.
Julien began his professional coaching career in the Quebec Major Junior Hockey League (QMJHL) for the Hull Olympiques, with whom he won the Memorial Cup in 1997.
From 2000 to 2003, he served as head coach for the AHL's Hamilton Bulldogs, the top minor league affiliate of the NHL's Montreal Canadiens.
In 2003–04, his first full season as an NHL head coach, he led Montreal to a 93-point performance (41–30–7–4 record) and the second round of the 2004 Stanley Cup playoffs.
[4] On October 6, 2006, he won his first game as Devils head coach with a 4–0 win against the defending Stanley Cup champions, the Carolina Hurricanes.
On April 2, 2007, Devils general manager Lou Lamoriello abruptly fired Julien with three games to go in the season.
Most notably, forward Patrice Bergeron and goaltender Manny Fernandez missed almost the entire season.
Injuries to star Bruins forwards David Krejčí (broken wrist), Marco Sturm (torn ACL) and Marc Savard (concussion), as well as defenceman Dennis Seidenberg (wrist) and an undisclosed injury to former Vezina-winning goaltender Tim Thomas (hip), were factors in the defeat.
The 2010–11 season saw Julien coach the Bruins to the third seed in the playoffs and a first-round matchup against the rival Montreal Canadiens.
In the Eastern Conference Semifinals, the Bruins got a chance to redeem themselves from the previous year in a much-anticipated series against the Philadelphia Flyers.
The Bruins, looking to rebound in Game 2, skated to a tie with Vancouver after regulation before a costly mistake by Boston captain Zdeno Chára after just 11 seconds of overtime allowed the Canucks to score the game-winning goal to take a 2–0 series lead.
The Bruins followed up that big win with another decisive victory, this time romping 4–0 over the Canucks while chasing goaltender Roberto Luongo, who had surrendered 12 goals in five periods during the two games in Boston.
On December 17, 2011, he collected his 200th regular season win as Boston's coach in a 6–0 whitewash defeat of the Eastern Conference-leading Philadelphia Flyers.
[10] The 2012 postseason, however, would not be as memorable for Julien's defending Cup champion Bruins, as they fell in the first round to the Washington Capitals and their upstart rookie goaltender Braden Holtby in seven games.
On June 5, 2015, Don Sweeney, the Bruins' new general manager, confirmed that Julien and his staff would be staying on for the upcoming 2015–16 NHL regular season.
[19] On August 12, 2020, following a loss to the Philadelphia Flyers in the Eastern Conference First Round, Julien experienced chest pains and was transferred to the hospital.
It was also announced that he would be returning to Montreal to rest, and the chances of him being able to rejoin the team before the end of the first round were described by Bergevin as "very minimal".
[24] On June 27th, 2024, St. Louis Blues President of Hockey Operations and General Manager Doug Armstrong announced Julien will be an assistant coach for the team in the 2024-2025 season.