British pop singer Rita Ora is the latest star to be cast in the upcoming adaptation of the sexy bestseller "Fifty Shades of Grey."

The 23-year-old singer will play the role of Mia, the adopted sister of Christian Grey, according to The Hollywood Reporter. Apparently, the character is new to the film and didn't exist in EL James' book, which the movie is based on.

On Monday, Ora shared the exciting news on her Twitter account writing, "It's official! I've been cast in @FiftyShades of Grey as Christian's sister Mia."

Although Ora is mostly known for her singing career, she has also appeared in an episode of "90210" and in the latest "Fast & Furious" movie, "Fast Six."

Last week, it was announced that Max Martini, the star of Hollywood movies like "Captain Phillips" and "Pacific Rim," will play the role of the bodyguard of lead character, Christian Grey.

According to the New York Daily News, the 43-year-old actor is reportedly set to take on the character of the bodyguard named Jason Taylor. Dakota Johnson, Luke Grimes, Eloise Mumford and Jennifer Ehle have also signed on to be in the movie directed by Sam Taylor-Johnson.

The erotic romance novel "Fifty Shades of Grey" became an international bestseller and has been translated in 52 languages since its release in 2011. So far, the "Fifty Shades" trilogy has sold more than 90 million copies worldwide in e-book and print, making it one of the fastest-selling book series in history.

"Fifty Shades of Grey" will open in cinemas on Valentine's Day weekend in 2015. The adaptation of the best-selling novel began filming this week in Vancouver.