Kuhnhackl was selected by the Pittsburgh Penguins in the fourth round (No. 110) of the 2010 NHL Draft and played the following season with Windsor of the Ontario Hockey League, where he scored 68 points (39 goals, 29 assists) in 63 games.
Kuhnhackl turned pro for the 2012-13 season, but injuries slowed his development and he spent time between Wheeling of the ECHL and Wilkes-Barre/Scranton of the American Hockey League. Considered a scoring-line winger, he changed his approach to become more of a two-way forward. Kuhnhackl made his NHL debut against the Montreal Canadiens on Jan. 9, 2016 and scored his first goal while shorthanded against the Tampa Bay Lightning on Feb. 20, 2016.