General manager Ron Francis said Tuesday the deal will pay Rask $4 million per year through 2021-22. Rask was a restricted free agent this offseason.
Francis says Rask has "gotten better every season that he's been a part of our organization" and called him a "big part of this team's present and future."
The 23-year-old had 48 points this past season -- the most in his career and the second most on the team -- with 21 goals and 27 assists in 80 games. He led the team with 18 points on the power play, with five goals and 13 assists with the man advantage.