[1] Her parents were Evelyn Bertha (née Bergstrom), who was of Swedish descent, and Henry John Olson, a physician.

[2] Olson was signed to a film contract by Paramount Pictures in 1948, and, after a few supporting roles, producers began to consider her for more prominent parts.

Her first big role came in Canadian Pacific (also 1949) with Randolph Scott, then Billy Wilder cast her for his upcoming project.

In Sunset Boulevard[1] (1950), she played Betty Schaefer, for which she gained an Academy Award nomination for Best Supporting Actress.

Olson's success in Sunset Boulevard also led to her being cast in the September 15, 1950, episode of the radio program Dimension X, titled "Hello Tomorrow".

Olson guest-starred on the Television series The Big Valley playing the mother of Ron Howard in the December 1, 1965, episode titled Night of the Wolf.