It was more on TV that Williams earned his name and face recognition, as a frequent guest on talk shows, game shows, and the variety shows of the 70s, including hosting four episodes of NBC's "The Midnight Special". He also appeared on several episodes of "The Love Boat" (ABC), and made his TV-movie debut in a small role in "Flight to Holocaust" (NBC, 1977). Williams joined Pat McCormick doing skits on several shows, and they also co-created the failed 1982 pilot "Rooster", produced by Glen A Larson, in which they hoped to star. Williams' TV legacy also includes theme songs for "The McLean Stevenson Show" (NBC, 1976-77), and "It Takes Two" (ABC, 1982-83). In the 70s and 80s, there was a flow of music, and Williams even took to the Las Vegas stage to perform his own songs, although at the time he had never even recorded them. With Roger Nicholls he wrote "Out in the Country" (1969), and other hits include "An Old Fashioned Love Song" (1972) and "Let Me Be the One" (1972).
Williams has frequently scored motion pictures as well, beginning with "The Getaway" (1972), and joined with John Williams (no relation) on "The Man Who Loved Cat Dancing" (1972) and "Cinderella Liberty" (1973), earning his first Academy Award nomination for the song "Nice to Be Around". He was also nominated for two Oscars for his score of "The Muppet Movie" (1979) and its song "The Rainbow Connection". On his own, Williams composed "The End" (1978) and "Ishtar" (1987). In 1992, Williams began doing the voice of The Penguin for "Batman: The Animated Series" on Fox Kids Network.