Nummedal made his FIS Freestyle Ski World Cup debut in January 2011 in Kreischberg.

During the 2013–14 FIS Freestyle Skiing World Cup he only competed once, but reached the podium, with a 3rd place in Silvaplana.

His second win came in the 2017–18 FIS Freestyle Ski World Cup, the big air in Mönchengladbach in December 2017, followed by his third in March 2018 in Québec City.

At the 2023 World Championships, he finished seventh in the big air event and won the silver medal in slopestyle.

After winning a World Championships medal, he stated that "The next big goal I can set for myself is another Olympics, and I don't have it in me.