Nermoen made his international debut in 2005 in the B-World Cup Nordic Combined. At the Junior World Championships 2006 in Kranj , he won the bronze medal with the team in the team competition. In Gundersen Nermoen reached 20th place. In the 2007/08 season he made his debut in the Nordic Combined World Cup . With 53 points, he reached 49th place overall. Since there were no successes in the following years, he has been competing in the Continental Cup since 2009.