Winningham made her feature debut in "One-Trick Pony" (1980) and was especially effective in "Threshold" (1981), as the first recipient of an artificial heart. Later feature roles, though, were either routine supporting parts ("Nobody's Fool" 1986, "Hard Promises" 1992), in films completely unworthy of her ("Turner and Hooch" 1989) or a combination of both ("St. Elmo's Fire" 1985). Winningham shone in the role of Mattie, the common-law wife of "Wyatt Earp" (1984) opposite Kevin Costner, and she had one of her best roles as a successful folk-rock singer coping with her sister's jealousy and addictions in "Georgia" (1995). The latter reunited her with the screenwriter Barbara Turner, who had penned two of Winningham's more successful TV-movies, "Freedom" (ABC, 1981) and "Eye on the Sparrow" (NBC, 1987).
Winningham has fared considerably better in her mainstay, the TV-movie, the restless aspects of her acting persona well-suited to the passionate Justine in "The Thorn Birds" (ABC, 1983), a recreation of the blind and deaf heroine of "Helen Keller--The Miracle Continues" (syndicated, 1984), the daughter of deaf parents longing to make a life on her own in the justly acclaimed "Love Is Never Silent" (NBC, 1985) and the undercover investigator torn in her loyalties in "Love and Lies" (ABC, 1990).