Like his older brother Daniel Forfang he represents the club Tromsø SK. Forfang made his World Cup debut in December 2014. He won team gold medal FIS Ski Flying World Championships 2016 with his teammates in Tauplitz/Bad Mitterndorf. His first individual world cup victory was in Titisee-Neustadt on 12 March 2016. In 2018 he won the last worldccup before the Olympic Games in Willingen. At the 2018 Olympic Games he gained a silver medal in normal hill individual and he is Olympic Champion 2018 with the Norway skijumping team (Andreas Stjernen, Daniel-André Tande, Robert Johansson).