CBS had Allen as a panelist on "What's My Line?" in 1953 when Sylvester 'Pat' Weaver, head of NBC's programming, was looking for a host for a concept he was nurturing--a late-night talk/variety series. Early efforts, such as "Broadway Open House", had not succeeded, but Weaver wanted to give "The Tonight Show" a try. Allen was hired by NBC to host the show and made it his own, molding the concept to a combination of monologues, guests, skits, and ongoing characters played by a repertory of actors including Louis Nye and Tom Poston. Allen sat behind a desk, asked questions and offered quick comebacks. The show was such a success that with the demise of Milton Berle's variety show, Allen became NBC's hottest property and the network added a 1956 Sunday night primetime variety show starring Allen. Within a year, the double-duty proved too exhausting for the host, so he relinquished "The Tonight Show" duties to Jack Paar and opted to work exclusively in primetime. The Sunday night show could not adequately compete with the already-established "Ed Sullivan Show" and by 1960, Allen was gone from NBC and trying to launch a variety series for ABC.
Allen's true TV stardom was to be a product of the 50s and he never really recaptured that luster. From 1964-66, he was the moderator of the panel show "I've Got A Secret" and in 1968 launched a syndicated bid to renew his talk show supremacy. But the world was turning towards the likes of Mike Douglas and Phil Donahue and Allen's talk show sputtered on for a few seasons before disappearing. In 1977, he launched a heralded PBS series, "Meeting of the Minds", which scripted the notion of what would happen if famous people from different eras could be interviewed today and encounter each other in modern times. Often appearing as a panelist was Allen's second wife, actress Jayne Meadows. Allen occasionally acted on TV, such as in an 1983 episode of "Fantasy Island", but more often played himself or a generic talk show host. On the big screen, he did play the title role in the glossy, hardly factual "The Benny Goodman Story" (1956), while in films such as "The Comic" (1969) and "Casino" (1995) he was cast as himself.
A prolific songwriter, Allen earned a Grammy for "Gravy Waltz" and also scored one motion picture, the 1968 MGM film "A Man Called Dagger", and numerous TV shows. He wrote special lyrics for the 1985 TV musical version of "Alice in Wonderland" (CBS). Into the 90s, Allen was a frequent guest on TV retrospectives and was saluted on PBS with a 1997 tribute in honor of his 75th birthday.