Stapleton went undrafted when he became eligible for the NHL draft. He then decided to play for two seasons with the Green Bay Gamblers of the USHL. Stapleton then represented the University of Minnesota Duluth for four seasons, where he led the team in scoring as a freshman, and had consecutive 40 point seasons.
Stapleton began his professional career by playing briefly with the Portland Pirates of the AHL. Stapleton played in 9 games with Portland, recording 5 assists. He then signed with Jokerit of the Finnish SM-liiga, completing a tryout which led to a one-year contract. During his first Jokerit season, Stapleton won the SM-liiga silver medal and finished second in playoff scoring.
On June 6, 2008, Stapleton signed as a free agent with the Toronto Maple Leafs. Stapleton was assigned to the Marlies on September 26, 2008. In his first season with the Marlies, Stapleton has proven to be a capable scoring threat, ranking near the top of team scoring leaders.