Mills began her career appearing in her first play at the age of nine. Two years later, Mills won Amateur Night at the Apollo Theater a record six times. The victory led to her being cast in her first role, the orphaned child of a runaway slave in the musical Maggie Flynn. In 1973, Mills' musical recording career was launched when she was signed to Paramount records by Michael Barbiero, and her first single "I Knew It Was Love" was released. She was later signed to Motown. Her first two albums there failed to generate a buzz as the label could not find Mills' sound and she left the label in 1976. Mills' career took a rise when she portrayed Dorothy in an African American adaptation of The Wonderful Wizard of Oz entitled The Wiz, where she began dating Michael Jackson. Filled with a more urban style of music and scenery, The Wiz made Mills a star particularly because of her stellar performance of the song "Home". It would become her signature tune for years, and would be covered later by Diana Ross for the big-screen adaptation three years later and by Whitney Houston for her dramatic musical performance debut on TV in the early 1980s. Mills was the teen-age star of the Broadway stage production of The Wiz. When she sang "Home", the musical's answer to "Somewhere Over The Rainbow", her theatrical delivery thrilled audiences and marked her as a talent to watch. One of her most appreciative fans was Michael. By his own count he saw The Wiz eight times, in part because of the up-coming film version but also because he and Stephanie had become friends. Like Michael, and Tatum O'Neal, she was a teen star burdened with adult pressures and popularity. Those close to the young star she was quite infatuated with Michael. At cabaret appearances around New York, Stephanie sang "I Wanna Be Where You Are" and used Jacksonesque stage mannerisms. But for Michael she was a good friend, nothing more. Later in her career she often sang a quite passionate version of "He's Out Of My Life", a female version of "She's Out Of My Life". Musical success was elusive until 1979, when signed under the 20th Century Fox Records record label, Mills found her breakthrough in disco music, recording songs such as "Put Your Body In It", "You Can Get Over", and "What Cha' Gonna Do With My Lovin'". The resulting album,"What Cha' Gonna Do with My Lovin'", was Mills' first gold record. She quickly followed the success with 1980's "Sweet Sensation", which featured Mills' biggest hit to date, the Reggie Lucas produced "Never Knew Love Like This Before". The single became a #12 R&B and #6 Pop hit in 1980, as well as reaching #4 in the UK Singles Chart. 1981's "Stephanie" featured a top hit for her and Teddy Pendergrass, entitled "Two Hearts", while her 1983 album, "Merciless", featured her hit "How Come You Don't Call Me Anymore?", as well as the #3 dance chart hit "Pilot Error", which was her first dance hit in the U.S. In 1984, Mills had her third UK hit with "The Medicine Song", which also reached #1 on the U.S. dance chart.