In 1990, Grönberg turned professional. After starting out on the second-tier
Challenge Tour, he was a member of the
European Tour from 1994 to 2003, winning four events in that timespan. His best finish on the European Tour Order of Merit was tenth in 1998. However, Grönberg was keen to join the
PGA Tour in the United States, repeatedly entering its
Qualifying Tournament. In 2003, after six failed attempts, he earned medalist honors. Grönberg had difficulty settling on the PGA Tour and after his 2005 second season he had to return to the Qualifying Tournament to retain his card, which he did. His best finish in a tour event was a 3rd place finish at the 2007
Valero Texas Open, three behind
Justin Leonard. In 2008, the first Mathias Grönberg Trophy event took place in Sweden. Grönberg's goal is to make golf more popular with young children in his home country. It is an annual event that is being played at Kårsta Golf Club. In 2009, Grönberg won his first title on the
Nationwide Tour at the
Melwood Prince George's County Open where he won by six strokes over
Esteban Toledo and
Justin Bolli. He finished 24th on the money list to earn his 2010 PGA Tour card. ==Personal life==