The 22-year-old Stewart led the team with 28 goals last season and finished with 64 points.
The deal’s terms weren’t disclosed.
Colorado general manager Greg Sherman says the team is looking forward to seeing Stewart “build on what he started a year ago.”
The Avalanche have made it a high priority to lock up some of their up-and-coming players, signing forward Brandon Yip and defenseman Kyle Quincey over the summer.
Colorado’s young team slipped into the playoffs last season as the eighth seed in the Western Conference. The Avalanche were eliminated in the first round by the San Jose Sharks.