Ellison began his career with the Cowichan Valley Capitals, a junior hockey team that is a part of the BCHL, in 1999–00. In his rookie season he was selected as the club's Co-Rookie of the Year. He played there for three years and received several honors including the Capital's Three Star Award winner and MVP, and led the team in scoring with 66 points in 2000–01 and again with 117 points in 2001–02. He was then drafted by the Chicago Blackhawks in the fourth round (128th overall) of the 2002 NHL Entry Draft.
He proceeded to play with the Red Deer Rebels of the WHL during the 2002–03 season before joining the Norfolk Admirals for the 2003–04 season of the AHL. He played two seasons with the Norfolk Admirals and was promoted to the Blackhawks to start the 2005–06 season.
On July 4, 2008, Ellison signed a one-year contract in Latvia with the Dinamo Riga of the Kontinental Hockey League. Ellison scored 39 points in 55 games, placing second with Riga in scoring for 2008–09. On August 4, 2009, he then signed a contract with fellow KHL team, HC MVD.
After three successful seasons with Torpedo Nizhny Novgorod, Ellison left the KHL and signed a one-year contract with Swiss club, EHC Biel of the NLA on June 26, 2013.[3] Ellison subsequently left Biel and returned to the KHL to play for Zagreb in the 2013–14 season. In 2014, Ellison signed a two-year contract with Belarusian club, HC Dinamo Minsk, starting from the 2014–15 season.
After three prolific seasons with Minsk, leading the club in scoring in his final two, Ellison left as a free agent to sign a lucrative two-year contract with larger Russian club, Metallurg Magnitogorsk, on June 7, 2017.[4]