During her career, Karlsson could not win any WTA or ITF tournaments, but reached two WTA finals in 1985. Her first was in doubles in Filderstadt , which she lost alongside Tine Scheuer-Larsen against Pam Shriver and Hana Mandlíková with 2: 6 and 1: 6. And three weeks later another individual final in Hilversum , which she lost against Katerina Maleewa with 3: 6 and 2: 6. She received greater attention in 1984 at the Wimbledon tournament , where she was the first qualifier to reach the quarter-finals.
For the Swedish Fed Cup team played nine games from 1994 to 1997, of which they won two.