He was born in Kristiania as a son of Gerda Ring and Halfdan Christensen and brother of Bab Christensen. He made his stage debut in 1949 at the National Theatre.
Christensen was born at Porsgrunn in Telemark, Norway. His family moved to Kristiania (now Oslo) where he attended Aars og Voss skole and later attended Kristiania Handelsgymnasium.