Markus Nilsen won the Whistler Cup giant slalom in April 2004 . He contested his first FIS races in December of the same year and celebrated his first victory a year later. After further victories and podiums, he made his debut in the European Cup on January 18, 2007 . He won first points on February 8, 2008 with sixth place in the giant slalom in Jasná , two weeks later he reached third place in Madesimo . Shortly afterwards he won the silver medal in the giant slalom behind the Austrian Marcel Hirscher at the Junior World Championships in 2008 in Spanish Formigal . In the previous year, Nilsen had just missed the medal ranks in fourth at the Junior World Championships 2007 in Flachau . At the Junior World Championship in Garmisch-Partenkirchen in March 2009 , the Norwegian remained without a result. On the first day of competition he had a hard fall in the Super-G, after which he had to pause for the rest of the winter.
After the 2008/2009 European Cup season was rather disappointing with only one top 10 place, Nilsen finished in the top ten four times in the 2009/2010 winter , finishing ninth in the European Cup giant slalom ranking . In the World Cup he was the first time in March 2008 at the start, remained at first but without points. After three top 10 results in the European Cup at the beginning of the 2010/2011 season , he was used again in the World Cup on December 19, 2010 on the Gran Risa in Alta Badia . He qualified for the second round in this giant slalom for the first time and won his first and so far only World Cup points with 29th place. In the European Cup he reached on January 28, 2011 with second place in the giant slalom of Méribel, his second podium, with which he achieved fifth place in the giant slalom discipline.