03/03/2015 01:12 EST | Updated 05/03/2015 05:59 EDT

Bo Levi Mitchell signs contract extension with Stampeders through 2018

Part of Calgary Stampeders starting quarterback Bo Levi Mitchell’s 25th birthday on Tuesday was celebrated at McMahon Stadium, only this time off the field with the announcement of his two-year contract extension.

The 2014 Grey Cup MVP, who was already signed through the 2016 Canadian Football League season, is now under contract through 2018.

On Nov. 30 at Vancouver’s B.C. Place Stadium, Mitchell capped his first season as the Stampeders’ starting pivot by leading Calgary to a 20-16 win over Hamilton in the championship game, its first Grey Cup title since 2008.

Mitchell completed 25 of 34 passes for 334 yards and an interception in the big game.

“I’ve thought the last few years, you need a quarterback to win championships, and Bo Levi is that quarterback,” Stampeders running back Jon Cornish said of Mitchell after last year’s Grey Cup win. “And it’s his first year as a starter.

“Henry Burris was a great quarterback, Drew Tate is a great quarterback … but Bo Levi took us to the championship.”

Earlier in the season, he became the first quarterback in CFL history to win 12 of his first 13 starts. But then Mitchell was felled by injuries to his knee and ankles, costing him three games.

Still, the six-foot-two, 196-pounder topped the league with a  98.3 QB rating, completing 264 of 417 passes (63.3 per cent) for 3,389 yards, 22 touchdowns and eight interceptions in 14 games. Mitchell has connected on 64.6 per cent of his pass attempts in three seasons with Calgary.