Devon was born in Glendale, California. His lengthy television credits included The Rifleman, The Virginian, Daniel Boone, The Monkees, Lassie, The Twilight Zone episode "Dead Man's Shoes" in 1962, and Mission: Impossible. He provided the voice of Batman on the pilot of a Batman radio program. Devon's film credits included the 1957 horror film The Undead, War of the Satellites, The Three Stooges Go Around the World in a Daze, and The Battle of Blood Island. He provided voice work on Ewoks.
Devon died of vascular disease on February 26, 2010 in Mill Valley, California.