Hagen has spent most of his career playing in events on the various Scandinavian tours, where he has collected several victories and finished top of the Nordic League Ranking in 2005.
His home club is Vestfold Golfklubb. He has also played many events over the course of six seasons on the second tier Challenge Tour, winning the Telia Challenge Waxholm in 2005. He has made just two appearances on the European Tour, the first in the 2005 Abama Open de Canarias and the second in 2006 at the OSIM Singapore Masters.
1991 Norwegian Junior Championship Challenge Tour (1) Nordic League wins (5) Other wins (2) Amateur Eisenhower Trophy (representing Norway): 1994, 1996.