Kristoffersen Hagen was raised in the youth ranks of Lillestrøm. He was signed by Grorud in 2018 and made his 2nd division debut for the club on 15 April. He played as a starter in the 1-2 win at Hønefoss, where he scored both goals for his team. In the 2019 championship, he contributed to Grorud's promotion to the Norwegian First Division.
