Cannon was a founding member of Joseph Papp's New York Shakespeare Festival, starring in their productions of The Taming of the Shrew (1956) and Much Ado About Nothing (1961).
His wife, Alice Cannon, appeared on Broadway in several productions including Company and Johnny Johnson. She also wrote Great Day In The Morning, which ran between March 28 and April 7, 1962.
Cannon also appeared in film roles, often as a cold-eyed villain. His film credits included An American Dream (1966), Cool Hand Luke (1967), Krakatoa, East of Java (1969), The Thousand Plane Raid (1969), Heaven with a Gun (1969), Cotton Comes to Harlem (1970), Lawman (1971), Scorpio (1973), Raise the Titanic (1980), Death Wish II (1982) and Beyond Witch Mountain (1982).
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, 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.
He wore a toupee in most of his later roles. The exception was the Remington Steele episode "Steele in the News" (4 March 1983), in which Cannon played a TV news anchor who only wore his toupee while broadcasting. He also appeared (with his toupee), that same season(#2), of Remington Steele in Episode 21 "Hounded Steele. In the second season of Twelve O'Clock High (1965–1966) he played Brig. Gen. Dave Creighton, who worked for Allied intelligence and helped to foil a plot by Nazi saboteurs in the 34th episode of the series, "RX For A Sick Bird".
Cannon died at his Hudson, New York home on May 20, 2005, aged 83. He was survived by his wife and two brothers.