The extension also includes a no-trade clause, which takes effect immediately. Steen will make salaries of $5.1 million, $5.8 million and $6.5 million, according to his agent.
The 29-year-old Steen is having the best season of his career with 22 goals and 36 points in 33 games. He was the first player in the NHL to score in each of the team's first 10 wins since Eric Lindros in 1993-94 and scored 20 goals in 24 games, a franchise best since Brett Hull in 1990-91.
Steen became the first Blues player to get a point in 13 straight games since Pierre Turgeon in 1999-2000. He's among the league leaders in most major categories and he and the Kings' Anze Kopitar are the only forwards in the NHL averaging over 15 minutes of even-strength time, two minutes of short-handed time and three minutes on the power play.
Information from The Associated Press and ESPN.com's Pierre LeBrun was included in this report.