He made his debut for Lillehammer FK in the 2011 Norwegian Second Division. In the autumn of 2011 he moved to attend the Norwegian College of Elite Sport in Bærum and play for Stabæk Fotball's youth team. He made his senior league debut for Stabæk in the loss against SK Brann in August 2012.
Trondsen signed for Sarpsborg 08 on March 5, 2015.
On August 14, 2017 he signed for Rosenborg BK.
anders trondsen skills and goals welcome to rosenborg hd 2017
Trondsen debuted for the Norway national football team in a 2-1 2018 World Cup qualification loss to Czech Republic on November 2016.