Career
He made his Alpine Skiing World Cup debut in Sölden in 2001. His best World Cup seasons were 2003 and 2004, where he finished eighth in the slalom standings. He represented Norway at the 2010 Winter Olympics.
Karlsen announced his retirement from competition in February 2013.
Since then he has worked as a personal trainer. He graduated from the Norwegian University of Science and Technology with a bachelor"s degree in History and Psychology in 2004, and started studies for a master"s degree in law at the University of Oslo in 2013.