Bernier's contract with the Ducks expired on 1 July 2017, leaving him an unrestricted free agent. The same day, he signed a one-year, $2.75 million contract with the Colorado Avalanche. However, his 2017–18 season with the Avalanche was riddled with injuries. Bernier suffered an upper body injury on October 25, 2017, in a game against the San Jose Sharks, and a head injury on February 16, 2018 which caused him to miss 10 games. Shortly after returning, he suffered a second head injury on March 10, 2018, in a game against the Arizona Coyotes, and in late March an infection kept him out for three games. The Avalanche made the 2018 Stanley Cup playoffs, where Bernier started Game 1 against the Nashville Predators due to an injury to first-choice goaltender Semyon Varlamov. Bernier was himself injured in Game 4 and was replaced by Andrew Hammond in the third period. Hammond started the following two games as the Avalanche were eliminated in six games.