Career
She plays as a defender or midfielder for AS Saint-Étienne of France"s Division 1 Féminine. Karlsson played for Kopparbergs/Göteborg Football Club (2002–2008) and Linköpings Football Club (2009–2010). In signing for Linköpings, Karlsson was known as Maria Karlsson II, or Maria "Kalle" Karlsson due to the presence of senior team–mate and namesake Maria "Kia" Karlsson.
Karlsson made 154 appearances in the Damallsvenskan, the highest level of women"s football in Sweden.
She also played in the Union of European Football Associations Women"s Champions League in 2009 and 2010. In January 2011 Karlsson became the first Swede to sign for a club in the new FA Forest, Snow and Landscape. After a successful trial, she signed a deal to play for Doncaster Rovers Belles while living at the Ramada Jarvis hotel in Doncaster.
At the end of the English season Karlsson returned to Sweden, signing for Jitex BK. After six Damallsvenskan appearances and one goal, in November 2011 Karlsson revealed she had departed Jitex and was considering a contract offer from Italian club Bardolino Verona. She signed a six–month deal to commence on 1 January 2012.
After moving on to Brescia, Karlsson transferred to French Division 1 Féminine team AS Saint-Étienne in August 2015.
These comprised eight caps at Under–17 level, 24 at Under–19 level and 25 at Under–21/23 level