Wahlgren started playing tennis at the age of eight and was ranked 8th among the Swedish juniors in 1982. After turning pro in 1985, he won his first Challenger tournament in Athens the following year . The final victory over the German Hans-Dieter Beutel , however, should remain his only single title. He was more successful in doubles in the following years, between 1987 and 1995 he won twelve tournaments on the Challenger Tour alongside various partners.
His best individual result on the ATP Tour was the final at the Sydney indoor tournament . On the way to the final, he beat number 3 seeded Carl-Uwe Steeb and defending champion Slobodan Živojinović . However , he clearly lost the game against Ivan Lendl in three sets, where he could only win five games. Wahlgren reached the final in Kuala Lumpur twice on the ATP Tour , but lost with his partner to the Dutch Jacco Eltingh and Paul Haarhuis .
He achieved his best scores in the world rankings in 1990 with 66th place in singles and in 1995 with 86th place in doubles. His best performance in a Grand Slam tournament was reaching the third round at the Australian Open in 1990 and 1992, when he was able to eliminate a seeded player with Brad Gilbert . In the doubles competition he reached the round of 16 at the 1995 Australian Open alongside Ola Kristiansson .
Wahlgren played his last match as a professional in November 2001 at the Challenger tournament in Caracas .
Sweden
Sydney
Ivan Lendl
Kuala Lumpur (1)
Jacco Eltingh Paul Haarhuis