In the
2005–06 season, two years into retirement from playing, Sacco was hired as an assistant coach for the
Lowell Lock Monsters, affiliate of the
Colorado Avalanche. On May 7, 2007, after two years as an assistant, Sacco was named head coach of the
Colorado Avalanche's new AHL franchise, the
Lake Erie Monsters. Sacco then led the Monsters for the next two seasons and while recording somewhat unimpressive season's numbers with limited resources was credited with helping development of younger players to the NHL. On June 4, 2009, a day after Avalanche head coach
Tony Granato was fired, Sacco was promoted and later introduced as the new head coach of the Colorado Avalanche for the
2009–10 season, a job former Avs great
Patrick Roy turned down days prior. After being projected finishing 15th in the
Western Conference by most ice hockey pundits, Sacco coached the Avalanche to the
2010 Stanley Cup playoffs posting a record of 43–30–9 in his rookie year of coaching in the NHL. Following the
2012–13 season, his fourth year at the helm, finishing last in the Western Conference and out of the playoffs for a third consecutive year, Sacco was relieved of his duties on April 28, 2013, ending his eight-year association with the Avalanche. On July 2, 2013, the
Buffalo Sabres hired Sacco as an assistant coach. On July 24, 2014, the
Boston Bruins hired Sacco as an assistant coach. On November 19, 2024, the Bruins named Sacco as interim head coach after
Jim Montgomery's firing. Sacco went 24-30-6 as interim coach as the Bruins finished last in the
Atlantic Division and missed the
Stanley Cup playoffs for the first time since the
2015–16 season. As the Bruins interviewed candidates for a new head coach, Sacco was among those involved. However, on June 2, 2025, it was reported that Sacco had been informed that he would not remain as head coach. On June 5, 2025, Sacco was named an assistant coach for the
New York Rangers. ==Career statistics==