 Hellner had a total of seven victories in the junior levels of cross-country skiing up to 30 km from 2003 to 2005.In Gällivare, Sweden, he took his first world cup win on a 15 km event.Hellner won bronze, his first medal, in the 4 × 10 km relay at the 2007 FIS Nordic World Ski Championships in Sapporo.