[1][2][3] Øyen was born in Trondheim, the son of the timber merchant Mikal Øien (1871–1922) and Amalie Rebekka Slåttelid (1878–1952).
After graduating from high school in 1921, Øyen traveled to the United States, where he worked as an accountant in Chicago.
In 1923, he received a bachelor's degree from California State University, and then worked for three years at the Norwegian Club in Chicago and at the same time performed in amateur theater.
From 1936 to 1938, Øyen was at the National Theater in Oslo and made a name for itself in two plays by Nordahl Grieg.
[1] Alongside his theater career, Øyen also performed as a film actor.