Sony Pictures announced the casting news, as well as the film's official title, in a press release on Wednesday. According to the studio, Tarantino has described the film as "a story that takes place in Los Angeles in 1969, at the height of hippy Hollywood."
DiCaprio stars as Rick Dalton, the former star of a Western TV series, while Pitt plays Cliff Booth, Dalton's longtime stunt double.
"Both are struggling to make it in a Hollywood they don’t recognize anymore," Tarantino explained. "But Rick has a very famous next-door neighbor... Sharon Tate."
"I’ve been working on this script for five years, as well as living in Los Angeles County most of my life, including in 1969, when I was seven years old," Tarantino remarked in Sony's release. "I’m very excited to tell this story of an L.A. and a Hollywood that [doesn’t] exist anymore. And I couldn’t be happier about the dynamic teaming of DiCaprio & Pitt as Rick & Cliff."
Tarantino previously worked with Pitt in 2009's Inglourious Basterds, set during World War II, and then collaborated with DiCaprio in 2012's Django Unchained, which took place in the South in 1858. This will mark the first time Pitt and DiCaprio have ever appeared together a feature film.
Once Upon a Time in Hollywood is set to hit theaters Aug. 9, 2019.