Gunnulfsen made his debut in the Scandinavian Cup in Meråker in February 2014 , where he was 55th in the sprint and 48th in the 30 km mass start race in classic technique. Gunnulfsen achieved his first point placement in the Scandinavian Cup in December 2014 in Lillehammer with 28th place over 30 km in the classic mass start. At the beginning of the 2015/16 season he placed in Vuokatti with 13th place over 15 km classic and 27th place over 15 km freestyle again in the points. At the Scandinavian Cup in Östersund in January 2016, he won the 30 km mass start race in the classic technique. He ran his first World Cup race in Drammen in February 2016 , which he finished in 33rd place in the sprint. At the U23 World Ski Championships in 2016 in Râşnov , he won the bronze medal over 15 km classic. In March 2016, he came 19th in the Scandinavian Cup at the mini tour in Otepää . He finished second over 10 km classic. At the end of the season he was ninth in the overall ranking of the Scandinavian Cup.
In the 2018/19 season, Gunnulfsen took eighth place in the 50 km mass start race in Oslo, his first World Cup points and won the Reistadløpet in April 2019 .
Norway
Ostersund