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.[4] 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.[5]
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.[6] 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.[3] His team was eliminated in the conference quarterfinals after six games by the San Jose Sharks. On April 28, 2010, Sacco was named a finalist for the Jack Adams Award alongside Dave Tippett of the Phoenix Coyotes and Barry Trotz of the Nashville Predators.[7] 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,[8] ending his eight-year association with the Avalanche.[9]
On July 2, 2013, the Buffalo Sabres hired Sacco as an assistant coach.[10]
On July 24, 2014, the Boston Bruins hired Sacco as an assistant coach.[7] In July 2024, he was promoted to associate coach.[2] On November 19, 2024, the Bruins named Sacco as interim head coach after Jim Montgomery's firing.[11]
