He was playing in vaudeville shows by 1911, appearing in Irving Berlin's ragtime musicals.

Harlan also played the role of Cap'n Andy in the first, part-talkie film version of "Show Boat" (1929).

In 1935, Harlan played the role of Starveling in Max Reinhardt's 1935 film version of Shakespeare's A Midsummer Night's Dream.

Contrary to popular belief, Harlan did not voice Mr. Mole in Bambi.

Mr. Mole was voiced by Bambi's story director, Perce Pearce.