Selected by the Colorado Avalanche in the second round (No. 33) of the 2009 NHL Draft, O'Reilly has 702 points (256 goals, 446 assists) in 991 regular-season games for the Maple Leafs, Blues, Sabres and Avalanche, and 65 points (25 goals, 40 assists) in 75 playoff games. He won the Conn Smythe Trophy as most valuable player of the postseason when he had 23 points (eight goals, 15 assists) in 26 games to help St. Louis defeat the Boston Bruins in seven games of the 2019 Stanley Cup Final.