Rita announced in December that she would be playing the role of Mia, the adopted younger sister of Jamie Dornan's male lead, Christian Grey - and she's now started filming her first scenes.
The 23-year-old popstar, who is filming in Vancouver, Canada, posted a photo to Instagram on Thursday night (16 January), perhaps giving fans a glimpse of what her character might look like on the big screen.
Rita wore a plunging low-cut top teamed with a black blazer. Sporting wavy voluminous locks, the 'Shine Ya Light singer smiled as she posed behind shelves of beauty products.
Rita, who has recently been at the centre of split rumours with DJ boyfriend Calvin Harris, will be acting alongside the likes of Jamie, Dakota Johnson, Luke Grimes, Eloise Mumford and Jennifer Ehle in the erotic film.
Taking to Twitter yesterday, Rita said: "Vancouver. It's beautiful here!"
This is Rita's biggest movie role to date, with her last appearance being a cameo in action movie Fast & Furious 6 last year.
Fifty Shades of Grey tells the story of billionaire Christian, who embarks on a passionate affair with student Anastasia Steele. The highly-anticipated film adaptation of E. L. James' bestselling novel is expected to hit cinemas on Valentines Day 2015.
Watch Rita's music video for 'Radioactive' below: