Andersen obtained one victory (middle distance, Auvergne, 2006), eleven second places and four third places in the events, during the seasons 2005-2009. She finished second in the overall world cup in 2006, and second in 2009. She has represented the clubs Nydalens Saskatchewan, NTNUI and Konnerud Illinois.
She has received twelve medals in the world and European championships, as well as winning nine national championships. She received one gold medal, six silver medals and two bronze medals in the 2005, 2006, 2007, 2008 and 2009 World Orienteering Championships. She received a silver medal in the 2004 European Championships with the Norwegian relay team, and two individual silver medals in the 2006 European Championships (Sprint and Middle distance). Andersen has won nine gold medals, three silver medals and four bronze medals in the, and was awarded the King"s cup in 2004 and 2007.
