Joaquin Phoenix to star in Ari Aster's new drama Disappointment Blvd.

Joaquin Phoenix is onboard to star in Ari Aster's new drama Disappointment Blvd.

The Oscar-winning actor will front the new project, which will be written and directed by the Hereditary and Midsommar filmmaker, according to Deadline.

Phoenix was rumoured to have been in negotiations to star in Aster's upcoming film late last year, but insiders told the outlet that the meetings were just discussions, and nothing was firmly agreed, until now.

Once the 46-year-old Joker star signed up to the project, it was pitched to buyers, with independent entertainment firm A24 snapping up Aster's film in a deal that will see them finance and produce Disappointment Blvd.

Details of the film are under wraps, but the plot has been described as "an intimate, decades-spanning portrait of one of the most successful entrepreneurs of all time." It's not yet known if the subject in the project is fictional, or based on a real person.

Aster and Lars Knudsen will also serve as producers on the flick.

A start date for production has not yet been confirmed, but Deadline reports that Phoenix will likely film this project before playing Napoleon Bonaparte in Ridley Scott's upcoming historical epic Kitbag.

The director is still in pre-production on his star-studded crime thriller Gucci, which could push filming on Kitbag to 2022.

Aster's critically-acclaimed psychological horror Hereditary, with Toni Collette and Gabriel Byrne, was a huge success back in 2018, and the 34-year-old filmmaker followed up his success with Midsommar, starring Florence Pugh and Jack Reynor, in 2019.