Ole-Kristian Tollefsen started his ice hockey career playing for Nes IK's youth teams, after one of his friends had talked him into it. He played for teams in the club until he turned 16, when he moved to Lillehammer, to attend the Norwegian College of Elite Sport. In Lillehammer, he is known as "Læfsa". Tollefsen played with Lillehammer Ishockeyklubb for two seasons, spending most of that time on the senior team, instead of any of the club's two junior teams where a player his age should have spent that stage of their career. During the 2001–02 season, he was a regular in the team's starting lineup as they reached fourth place in the Norwegian Elite League, and reached the playoff semi-finals for a bronze medal. He also played for both the junior teams in their playoffs, getting a silver medal with the Elder Junior team, and the gold medal with the Younger Junior team. The medals were the last thing he accomplished in the Norwegian league system thus far in his career.
For the 2005–06 season he started the season in the AHL, but on November 23, he got his NHL debut in a 4–2 loss against the Phoenix Coyotes. He played an additional four games for the Blue Jackets, with two penalty minutes, before he was sent down to Syracuse again, where he spent the rest of the season. He played in 70 of the Blue Jackets' games in the 2006–07 season. On November 10, he, and fellow Norwegian NHL player Patrick Thoresen played in the first NHL game ever to have two Norwegian players facing each other, when the Blue Jackets hosted Thoresen's Edmonton Oilers. In Ken Hitchcock's debut as the coach for the Blue Jackets, a November 24 away game against the Philadelphia Flyers, Tollefsen had his first career NHL point when he assisted on Jason Chimera's second period goal, he scored his first goal against the Chicago Blackhawks on March 20, 2007. He started a scoring streak when he forced overtime against Detroit Red Wings in the next game, tying Espen Knutsen's Norwegian NHL record. He accumulated 123 penalty minutes during the season, including fights against Mark Smith, Joffrey Lupul, Jordin Tootoo, and Bill Guerin. On July 30, 2009, Tollefsen signed a one-year contract with the Philadelphia Flyers. On February 6, 2010, Tollefsen, along with a 5th round pick in the 2011 NHL Entry Draft, was traded to the Detroit Red Wings for Finnish forward Ville Leino. In January 2018 Tollefsen officially announced his retirement.
International play
Tollefsen played in three matches for Norway during the 2010 Winter Olympics, with no points. He received a 25-minute penalty after checking Slovakia'sĽuboš Bartečko in the head during the quarterfinal play-in game on February 23, 2010.
