He is chairman of Orkla, where he is a major shareholder, and holds large stakes in Steen & Strøm, Jernia and Komplett through his family company Canica.

According to Forbes, Hagen is worth US$2.1 billion, making him the sixth richest person in Norway.

Hagen is educated at Kjøpmannsinsituttet (now part of the BI Norwegian Business School).

He founded the RIMI discount store chain along with his father in the 1970s, and retained ownership until the 2000s, when he sold to Swedish ICA and Ahold.

[citation needed] Stein Erik Hagen has three children from his first marriage, and a son from a later relationship.