The 26-year-old forward could have become a restricted free agent Wednesday. He was traded to the Blues by the New York Rangers for forward Sammy Blais on July 23. New York also received a second-round pick in the 2022 NHL Draft.
"I'm just happy it's happened," Buchnevich said Wednesday. "I don't need to wait anymore and I know where I will be the next four years.
"Obviously they have a lot of good players. Obviously tough to play [against]. A good goaltender. I hope I play a big role there and help the team."
Buchnevich scored an NHL career-high 48 points (20 goals, 28 assists) in 54 games with the New York Rangers last season. He tied Chris Kreider for second on New York in goals and was fourth in points.
"I'm excited to have Pavel join our group," Blues general manager Doug Armstrong said. "... He's got good size at 6-3. He is a left shot, can play the right side. He's scored in the league recently. He's 26 years old. ... A very good penalty killer too, a very underrated penalty killer. So he's going to touch all aspects of our game and he's at a good age as we continue to retool this roster, and I think he's a good piece for us."
Selected by the Rangers in the third round (No. 75) of the 2013 NHL Draft, Buchnevich has scored 195 points (79 goals, 116 assists) in 301 regular-season games and has one assist in eight Stanley Cup Playoff games.
"I think he's a definite top-six forward," Armstrong said. "You look at the minutes that he averaged last year (18:44), where he finished in scoring on the Rangers, I think he's just starting to come into his own."
NHL.com independent correspondent Louie Korac contributed to this report
