He is mainly known for his compositions for numerous Disney films from the 1950s to the 1970s, among them Sleeping Beauty (1959), One Hundred and One Dalmatians, The Absent-Minded Professor (both 1961), The Sword in the Stone (1963), The Jungle Book (1967), The Love Bug (1968), The Aristocats (1970), and Robin Hood (1973).

After graduating from Oregon State University, he worked as a bandleader at the Multnomah Hotel in Portland before relocating to Los Angeles to further pursue a musical career.

Over the course of his career, Bruns was nominated for four Academy Awards for his work on Disney films, including Scoring of a Musical Picture for Sleeping Beauty and Babes in Toyland (1961), and Best Adaptation or Treatment for The Sword in the Stone.

[2] He attended and graduated from Sandy High School,[2] and went on to study engineering at Oregon State University, where he was a member of Lambda Chi Alpha fraternity.

[2] In 1946 he was appointed musical director at radio station KEX in Portland, and also was the bandleader for the Rose Bowl room of the Multnomah Hotel.

In the late 1940s, he moved to Los Angeles, where he did studio work, performed, and recorded with trombonist Turk Murphy's Jazz Band.

[2] He instructed music part-time at Lewis & Clark College and continued to perform and compose, including recording at least one locally distributed album of jazz.