Born in Copenhagen, Arentoft started playing football with Copenhagen club Brønshøj Boldklub. He made his Danish national team debut in June 1965, and played four national team games while at Brønshøj.
A Danish footballer born in Copenhagen began his career with Brønshøj Boldklub before making his international debut for Denmark in June 1965. His time at the club also included appearances for the national team.