From 1999, Andersen, who started for the Isfjorden IL club, jumped in the Continental Cup (COC). However, the first season was unsuccessful. In the end, with only five COC points won, he was only able to achieve place 127 in the overall ranking. In the following season the jumping was more successful, so that in the end he finished 34th in the overall Continental Cup with 286 points.
At the Junior World Championships in 2000 in Štrbské Pleso , he won the silver medal in team jumping together with Erik Leine Wangen , Thomas Lobben and Anders Bardal . The team only had to admit defeat to the team from Austria . On March 19, 2000, Andersen jumped in the ski jumping World Cup for the first time and was able to win his first World Cup points with 23rd place in ski flying in Planica . In the end, he finished 70th in the overall World Cup ranking for the 1999/2000 season . In the following three World Cup competitions at the beginning of the 2001/2002 season, which Andersen denied, he remained pointless. From December 26th, 2001, he will only start again in the Continental Cup. Already in his first competition he came 8th on the normal hill in St. Moritz . At the end of the season he was 78th in the overall Continental Cup ranking with 129 points. Andersen competed his last international jumping on August 25, 2002 on the Marikollen in Rælingen .