Author EL James broke the suspense Monday morning when he tweeted "I am delighted to let you know that the lovely Dakota Johnson has agreed to be our Anastasia in the film adaptation of Fifty Shades of Grey."
Johnson is 24 years old and is the daughter of Don Johnson and Melanie Griffith.
Johnson had small movie roles in The Social Network and The Five Year Engagement but is best known for her part in the TV sitcom Ben and Kate.
It wasn't long before James added to that with another tweet saying "the gorgeous and talented Charlie Hunnam" would take the role of Grey.
The series of books is about a college student who has a racy affair with a rather adventurous billionaire.
The Hollywood Reporter points out Universal Studios won a bidding war for the rights to the books calling them "a complex love story, requiring a delicate and sophisticated hand to bring it to the big screen."
Others have called them nothing more than soft-core pornography but the series has been massively successful selling over 70 million copies.
See more of the cast and other info here.