Lehmann played for AIK in the Swedish Elitserien for five seasons from 1982 to 1987. Selected by the Boston Bruins of the National Hockey League in the 1982 NHL Entry Draft, he joined Boston for the 1987–88 season, and played nine games that season, and a further 26 games the following season, spending most of those two years playing for the Bruins' American Hockey League affiliate Maine Mariners. He was traded to the Edmonton Oilers before the 1989–90 season, but played in only one game for the club. Lehmann played in 19 regular season games and 6 playoff games for the Cape Breton Oilers before returning to Sweden. Lehmann played for seven more years in the Elitserien, mostly for AIK, but also for MODO for one season, and one game for Södertälje in his final season, before retiring in 1997.