Tilton had early roles on such television series such "Happy Days" and "Eight Is Enough". She made her first film appearance alongside Jodie Foster in "Freaky Friday" (1976). In 1978, Tilton made a cameo appearance in the John Milius film "Big Wednesday". The following year, she made her big break by landing the role of Lucy Ewing, the sly, vixenish, frequently frustrated granddaughter of John "Jock" Ewing Sr. and the former Eleanor "Ellie" Southworth on the television series "Dallas", alongside actors Jim Davis, Barbara Bel Geddes, and Larry Hagman, from 1978 to 1985 and from 1988 to 1990. She also appeared on one episode of the series' spin-off "Knots Landing" in 1980. At the height of her "Dallas" fame, she received a $50,000 salary per episode, appeared on 500 magazine covers, and drew 65 million viewers for her 1981 TV wedding.