She rose to stardom as "Dorothy" in the original seven-time Tony Award winning Broadway run of the musical The Wiz from 1974 to 1979.

Her albums What Cha Gonna Do with My Lovin, Sweet Sensation and Stephanie went gold or platinum, all through 20th Century Fox Records.

[10] After winning Amateur Night at the Apollo Theater six weeks straight at age eleven, Mills went on to become the opening act for the Isley Brothers.

Mills's career took a rise when she portrayed Dorothy in the seven-time Tony Award winning Broadway musical The Wiz, an African-American adaptation of The Wonderful Wizard of Oz.

[13] The song "Home" was first performed by Mills in the stage production and would be covered later by Diana Ross for the movie adaptation three years later.

[14][15] Mills’s commercial success in the music industry remained elusive until 1979, when she signed to the 20th Century Fox Records label.

There, Mills found her niche in mainly disco music, recording songs such as "Put Your Body In It", "You Can Get Over", and "What Cha Gonna Do with My Lovin'".

[19] Success for Mills had peaked until 1986, when her version of the Angela Winbush-penned "I Have Learned to Respect the Power of Love", hit #1 on the R&B singles chart.

The set was produced by Donald Lawrence and featured a spiritualized retooling of her hit "I Have Learned To Respect The Power Of Love".

In 2015, Mills was cast as Aunt Em in the NBC live musical production of The Wiz, forty years after her initial Broadway run in the show.