Earlier this week it was believed that Baldwin had left the musical for unknown reasons, but director Adam Shankman has now officially confirmed that Baldwin is still on board.
"Full cast read through and rehearsal today on #rockofagesmovie, and that includes Alec Baldwin!" Shankman tweeted on Thursday.
The musical follows a love story set in '80s Hollywood to a soundtrack of artists like Bon Jovi, Poison, and Journey.
The film's ensemble cast already includes Tom Cruise, Julianne Hough, Russell Brand, Paul Giamatti, Malin Akerman, Bryan Cranston and Catherine Zeta-Jones.
Rock of Ages is scheduled to begin production later this month.