Knotts got his first major break on television in the soap opera "Search for Tomorrow" where he appeared from 1953 to 1955. He came to fame in 1956 on Steve Allen's variety show, as part of Allen's repertory company, most notably in Allen's mock "Man in the Street" interviews, always as an extremely nervous man. He remained with the Allen program through the 1959–1960 season. From October 20, 1955, through September 14, 1957, Knotts appeared in the Broadway play version of "No Time for Sergeants", in which he played two roles, listed on the playbill as a Corporal Manual Dexterity and a Preacher. In 1958, Knotts appeared for the first time on film with Andy Griffith in the film version of "No Time for Sergeants". In that film, Knotts reprises his Broadway role and plays a high-strung Air Force test administrator whose routine is disrupted by the hijinks of a provincial new recruit.