In 1970 Cannon appeared as Roy Harkness on "The Men From Shiloh" (rebranded name for the TV western "The Virginian" in the episode titled "Hannah." He played a recurring character - a lawman named Harry Briscoe working for the Bannerman Detective Agency - in the 1971 to 1973 western series, "Alias Smith and Jones". He guest starred in many series over the years, including "Wagon Train", "Gunsmoke", "Lancer", "The Fugitive", "Voyage to the Bottom of the Sea", "The Untouchables", "The Wild, Wild West", "East Side/West Side", "The Invaders", "Combat!", "Stoney Burke", and the miniseries "Testimony of Two Men" (1977) and "Top of the Hill" (1980). He was cast in several episodes of CBS's "Murder, She Wrote". His last television acting appearance was on an episode of "Law & Order" in 1991.