Nilsen made his debut in the World Cup on January 11, 2014 in the freestyle sprint in Nové Město na Moravě , where he reached 19th place, with which he was able to place himself in the points. He succeeded in doing this again at his next start in Drammen in March 2014 with rank 16. The 2013/14 season ended Nilsen at No. 59 in the Sprint Cup and ranked 112 in the World Cup. In his first World Cup appearance in the 2014/15 season in the sprint in Otepää , he achieved his first top 15 result in the World Cup with 12th place.