Pahlsson, born December 17, 1977 in Ornskoldsvik, Sweden was a strong defensive forward for MoDo in Sweden when he was drafted 176th overall in the 1996 Entry Draft by the Colorado Avalanche, who used their tenth pick.

Pahlsson finished his career with Modo, enjoying his best season in 1998-99 when he tallied 17 goals and 34 points. But Raymond Bourque had expressed his desire to win a Stanley Cup before he retired, and the Bruins, who were not going to give Bourque that opportunity in the near future, relented and sought eager takers for the star defenseman. The best deal, both for Bourque and the Bruins, came from Colorado, who shipped Sami Pahlsson along with Brian Rolston, Martin Grenier and a first round draft choice to Boston for Bourque and forward Dave Andreychuk on March 6, 2000. Sami joined the NHL that fall, making his debut as a Bruin in the season opener October 5, 2000 against the Ottawa Senators. But after just 17 games, Pahlsson was traded to the Mighty Ducks of Anaheim for Patrick Traverse and Andrei Nazarov. Sami finished the season as a Mighty Duck, scoring 4 goals and 9 points as an NHL rookie.

Over the course of the next four seasons, Pahlsson has shown his worth as a strong defensive centre with excellent faceoff skills. In 2002-03, the former Avalanche prospect helped the Mighty Ducks reach their first Stanley Cup final, only to lose in a hard fought seven game series to the New Jersey Devils. Over the course of the next few seasons, Pahlsson established himself as one of the leagues top defensive forwards and excelled in defensive situations. In 2006-07, Pahlsson's career year included a personal best 26 points and a nomination for the Frank J. Selke Award. During the playoffs that season, he represented the Ducks in all 21 games en route to the 2007 Stanley Cup.

On the international scene, Pahlsson represented his homeland at the 1996 World Junior Championship and is a four-time member of Sweden's World Championship team (1999, 2000, 2004 and 2005), in the Olympics Pahlsson earned a Gold Medal in 2006 as Sweden defeated Finland.

After parts of eight seasons in Anaheim, Pahlsson was sent to the Chicago Blackhawks at the trade deadline in exchange for defender James Wisniewski.

In the summer of 2009 Pahlsson would again be on the move. This time he found himself an unrestricted free agent and signed with the Columbus Blue Jackets on July 1st.

After two and half seasons with the Blue Jackets, Pahlsson would find himself on the move again. This time dealt to the powerful Vancouver Canucks in exchange for a pair of fourth round draft picks.