Mathisen is from Vadsø and comes from the position as the leader for the development of sustainability strategy and sustainability systems at Varanger Kraft. He is the leader of the Vadsø Centre Party and a board member of the Finnmark Centre Party.

Mathisen is a former manager in the fishmeal industry, director of Innovation Norway Finnmark, and business advisor in Finnmark County Municipality. He holds a cand.mag. degree from UiT in economics and public policy.