In the 1930s he worked as a musician with various groups in the Portland, Oregon area. In 1946 he was appointed musical director at radio station KEX in Portland, Oregon, and also was the bandleader for the Rose Bowl room of the Multnomah Hotel. From 1947 to 1949 he performed and recorded on trombone with Portland's Castle Jazz Band, led by banjoist Monte Ballou.

In the late 1940s he moved to Los Angeles, where he did studio work, and performed and recorded with trombonist Turk Murphy's Jazz Band. In 1953 he was hired by Walt Disney as an arranger, eventually becoming Disney's musical director, a position he held until his retirement in 1976. Despite his retirement he continued to work on Disney projects.

Among his work is the song "Yo Ho (A Pirate's Life for Me)" (which he co-wrote with Xavier Atencio), used in the Disney theme park attraction Pirates of the Caribbean and the movies based on that ride. He also co-wrote "The Ballad of Davy Crockett" with Tom W. Blackburn, as well as the song "Love" for the Disney animated film Robin Hood. During the mid-1950s, he adapted the music from Tchaikovsky's Sleeping Beauty ballet for use as background score in the 1959 Disney film version. He also composed the score for The Jungle Book, and provided Herbie the Love Bug with his sprightly theme song, featured prominently throughout the series.

During his tenure with Disney Studios, Bruns continued to play dixieland jazz, leading his Wonderland Jazz Band on two recording sessions, and playing and recording occasionally with the Disney "house" band, the Firehouse Five Plus Two.

Bruns retired from Disney in 1976 and moved back to Sandy, Oregon.He taught part-time at Lewis & Clark College and continued to play and compose music, including recording at least one locally distributed album of jazz.-Wikipedia