Pärson won the Alpine Skiing World Cup overall title in 2004 and 2005. The latter title was won by the smallest margin ever, only 3 points over her fierce rival, Janica Kostelić. Initially a slalom and giant slalom specialist, she won her first Super-G and downhill races in March 2005 at San Sicario, Italy, during the pre-Olympic competitions. In total, she has won 42 World Cup races in all five disciplines.
Pärson has won seven gold medals in the FIS Alpine World Ski Championships, in 2001 (slalom), 2003 (giant slalom), 2005 (giant slalom, Super-G) and 2007 (Super-G, Super-combined, downhill). These go along with two silver and three bronze medals in other events in 2001, 2005, 2007 and 2011. With her three gold medals in 2007 at Åre, Sweden, she became the first skier in history to win World Championship golds in all five disciplines.
Pärson has earned a total of 17 individual medals in World Championships and Olympics, exceeding the record by Christl Cranz in women's alpine skiing. In men's alpine skiing this achievement has been beaten only by Kjetil André Aamodt, with 20.
After two disappointing seasons (2006/07 and 2007/08 where she finished fifth and sixth in the overall cup), she was back to her best over the 2008/09 season, finishing third in the overall cup.
At the 2010 Winter Olympics, while trying to chase down eventual downhill champion Lindsey Vonn of the United States, Pärson lost her balance on the last jump before the finish, resulting in a 60-metre flight and subsequent fall, without however suffering serious injury. She recovered from the fall and one day later won the bronze medal in the Combined event.
After living several years in Monaco during her sports career, she returned to Sweden and lives in Umeå since 2012. In June 2012, Pärson announced on the Swedish radio program Sommar that she has been in a relationship with a woman for the past five years, and that they are expecting a child together. Their son, Elvis was born on 4 July 2012.