'Spencer' is set for release in November.
Kristen Stewart will play Princess Diana in Pablo Larrain's biographical drama and it will receive a theatrical release on November 5 and will premiere at the Toronto and Venice film festivals.
The movie had been expected to come out in 2022 to coincide with the 25th anniversary of Diana's death but will now be released with an eye towards the awards season.
Kristen plays the late Princess of Wales – who was born Diana Frances Spencer – in the film, which takes place over a few days over Christmas 1991 at the Queen Elizabeth's Sandringham Estate as Diana decides to end her marriage to Prince Charles.
'Peaky Blinders' creator Steven Knight has written the script with Jack Farthing portraying Prince Charles in the film. Timothy Spall, Sean Harris and Sally Hawkins also feature in the ensemble.
The flick is being produced by Juan de Dios Larrain for Fabula Films, Jonas Dornbach and Janine Jackowski for Komplizen Film and Paul Webster for Shoebox Films.
Kristen previously admitted that "she can't stop thinking about" the princess – who was tragically killed in a car accident in 1997 – as she threw herself into researching the royal, even falling asleep to the sound of her voice.
The 31-year-old actress said: "Getting to know Diana has been a really cool experience.
"She means a lot to me – but it’s all relatively new because I’m from LA and I didn’t grow up in England.
"Before this, she was not something that was at the forefront of my mind, because I lived so far away from it all.
"Now, I can’t stop thinking about her. I often wonder what she’d think about what’s going on in the world right now.
"To be honest, I’ve now consumed pretty much all there is to consume in terms of videos and interviews. I’ve watched everything that you could hear or see. I even go to sleep with it on."