On 4 October 1956, Gardiner appeared with Greer Garson as the first two guest stars in the series premiere of NBC's The Ford Show, Starring Tennessee Ernie Ford. In 1956, he was the guest star on "The Millionaire" on the episode "The Story Of Waldo Francis Turner". He made other guest appearances on television sitcoms of the 1960s, including Fess Parker's ABC series, Mr. Smith Goes to Washington and Stanley Holloway's Our Man Higgins. He also appeared in the 1964 Perry Mason episode, "The Case of the Ugly Duckling," as Business owner Albert Charity, and in an episode of Alfred Hitchcock Presents ("Banquo's Chair"). His last major role was alongside Phyllis Diller in her 1966-1967 ABC series, The Pruitts of Southampton. Also in 1967 he made a guest appearance on Petticoat Junction, in the episode "Uncle Joe and the Master Plan", as Gaylord Martindale.