Kajsa grew up in Sollentuna, north of Stockholm, with her mother Elsa, father Gunnar and big brother Anders. Her interest in sport began when she was six years old and tried sports such as football, volleyball, badminton, swimming and cross-country skiing, none of which was able to keep her interest.When she was ten years old, she was persuaded by her big brother, Anders, to compete in Rösjöloppet, a long-distance track event. After that event, she began to try out sevaral athletic events.Kajsa continued to train in several athletic events until she was 15 years old, when a new coach, Bengt Jönsson, came to her club, Turebergs FK. Soon after his arrival, he and Kajsa chose to concentrate on the event that was her best, high jump.

In 2001 she moved from Sweden to Monaco.

By 2004, lack of progress and long travel distances caused Kajsa to end the relationship with her coach, Bengt Jönsson. She joined a group of athletes (including Olympic gold medalist Christian Olsson) under Yannick Tregaro. At a competition in Båstad, on July 18, 2004, Kajsa tore her Achilles tendon. Due to the injury, she missed the 2004 Summer Olympics in Athens, but managed to return to form just in time for the 2005 World Championships in Athletics in Helsinki. There she made an impressive series of jumps to edge out Chaunte Howard for the gold medal.

She has currently, as of July 24, 2006, been ranked the number one female high jumper in the world for 50 consecutive weeks, since August 8, 2005.

In Arnstadt Germany, 4th of February 2006, Kajsa set her first world record. A first attempt indoor leap of 2.08m to surpass Heike Henkel's 2.07m leap on 8th of February 1992.

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