Kristen Stewart appears as Diana, Princess of Wales in a first-look snap of the actress in the role.
The Twilight actress, 30, stars in Spencer, which focuses on a weekend in the early 1990s when Diana decided her marriage to the Prince of Wales was over.
US star Stewart said: "Spencer is a dive inside an emotional imagining of who Diana was at a pivotal turning point in her life.
"It is a physical assertion of the sum of her parts, which starts with her given name – Spencer.
"It is a harrowing effort for her to return to herself, as Diana strives to hold on to what the name Spencer means to her."
It comes after Emma Corrin appeared as Diana in The Crown, which featured the unravelling of the marriage.
The new film sees Diana spend Christmas with the royal family at Sandringham and decide to leave her marriage.
Spencer is written by Steven Knight, creator of Peaky Blinders, and filming will take place in the UK and Germany.
It is expected to launch in the autumn, ahead of the 25th anniversary of Diana's death in 2022.
Producers have not yet revealed who will play Charles.
Others cast in the film, directed by Pablo Larrain, include Timothy Spall, Sally Hawkins and Sean Harris.
The Crown sparked calls by Culture Secretary Oliver Dowden to add a disclaimer to episodes saying it is a work of fiction, a request which streaming giant Netflix denied.