The 20-year-old Just Keke host will portray the princess in Rodgers & Hammerstein's Cinderella beginning September 9. Palmer is succeeding Paige Faure, and the role is her first on Broadway.
"I don't really celebrate," she told Vanity Fair on Friday. "And besides, I still don't believe it is real!"
Palmer mentioned she "always had an idea to approach Broadway for an audition," and said, "Thinking about that [live audience] gives me energy. Seeing that many people in the audience, who you can't recognize, that's what excites you and gets you pumped."
"I'm sooooo excited to be doing broadway for the first time, as Cinderella!!" she tweeted Monday. "DREAMS DO COME TRUE!!"
Palmer is the youngest television talk show host in history, and has also appeared in films Akeelah and the Bee and Joyful Noise. She recently guest starred as Kyrie Eleison on Showtime series Masters of Sex.
Just Keke airs at 5 p.m. ET weekdays on BET.