Warner Bros. confirmed the news with The Hollywood Reporter, revealing that shooting will start as early as September with a rumoured budget of around $55 million - not a huge amount by blockbuster standards.
But now Phoenix has reportedly finalized his deal to play Joker in this untitled standalone, which Phillips-the filmmaker behind The Hangover trilogy and the crime film War Dogs-will direct from a script he co-wrote with Scott Silver.
The Joker movie has been a bit of an enigma amongst DC Comics fans, ever since it was first announced in September of past year. Variety originally reported in February that Phoenix was in talks for the role. The film will be produced by Emma Tillinger Koskoff and executive produced by Richard Baratta.
"I don't know... it could be an interesting character".
Pictures announced today that Joaquin Phoenix will star in an origin story of one of DC's most notorious Super-Villains, the Joker. I don't really care about the genre, I care about the character and the filmmaker.
No official release date has been set, but THR claims the film could be in theaters by late 2019.