Beginning his career with Landskrona BoIS in 2003, he went on to represent NEC Nijmegen, West Bromwich Albion, and Djurgårdens IF before retiring at Wigan Athletic in 2019.

New West Brom manager Roberto Di Matteo made Olsson the club's new vice-captain as they prepared for a season in the Championship.

Olsson played a pivotal role as West Brom secured promotion back to the Premier League at the first attempt.

He then made his return to the starting line-up against Blackburn Rovers on 23 January 2011, completing the full 90 minutes, partnering Gabriel Tamas in defence in a 2–0 defeat at Ewood Park.

In February 2012, Olsson again played a key role in a historic West Brom win, scoring Albion's second goal in a 5-1 demolition of Wolverhampton Wanderers in the Black Country derby at Molineux.

On 6 October 2012, it was announced that Olsson had signed a new four-year contract with West Bromwich Albion, ensuring he would remain with the team until 2016.

The 2014-15 season saw Olsson's first team opportunities limited due to the arrival of 26 time England international Joleon Lescott as well as niggling injuries.

Olsson started in what would prove to be the last of his 261 appearances for West Brom in a 4-0 away defeat to Tottenham Hotspur in January 2017, before his contract was mutually terminated in March.

Olsson remains a fan favourite at West Brom and is considered a key figure in the club's prolonged stay in the top flight between 2010 and 2018.

[18][19] He decided to return to Sweden after facing stiff competition for playing time at West Bromwich, with only 7 club appearances in his final season.

Olsson has signed up with Viasat and will appear via satellite link and telephone to provide a players perspective on the matches and the Premier League.

He lists Bob Dylan, Nirvana, The Rolling Stones, Oasis, Babyshambles, Mando Diao, The Chardogs and The Who as some of his favourite artists.