Career
He played six seasons for the Malmö Redhawks in the Swedish Elitserien prior to his National Hockey League career. Johnsson was selected 286th overall by the New York Rangers in the 1994 National Hockey League Entry Draft, the last pick in that draft. After playing two seasons with the Rangers, he was traded to the Philadelphia Flyers on August 20, 2001, along with January Hlaváč, Pavel Brendl, and a 3rd-round pick for Eric Lindros.
After four seasons with the Flyers, Johnsson signed a four-year contract with the Minnesota Wild on July 1, 2006.
On February 12, 2010, Johnsson and Nick Leddy were traded to the Chicago Blackhawks for Cam Barker. He played 8 regular season games for Chicago before getting injured.
Johnsson missed the remaining 14 regular season games and all 22 playoff games because of a concussion. Johnsson did play 60 games in the 2009-2010 season.
Johnsson never played again after receiving his concussion.
Played for Sweden in the XIX Olympic Winter Games.