The Brat Pack actress has become the latest addition to Jon M Chu's adaptation of the cult 1980s cartoon, according to The Hollywood Reporter.
Juliette Lewis also joined the project this week.
The film will star Aubrey Peeples as Jem, Stefanie Scott as Kimber, Hayley Kiyoko as Aja, Aurora Perrineau as Shana and Ryan Guzman as Rio.
Christy Marx launched the show in 1985. The adventures of Jerrica Benton and her secret rock star alter ego ran for three seasons.
Ringwald is best known for her starring role in '80s teen classics including Pretty in Pink, The Breakfast Club and Sixteen Candles. She was most recently seen in The Secret Life of the American Teenager.
Jem and the Holograms is yet to announce a release date.