The upcoming caper is an offshoot of Suicide Squad, of which critics agreed she was the strongest player.
The Harley Quinn film is called Birds Of Prey and will have an R-rating – giving it more freedom than Suicide Squad, which was PG-13.
She told Flickering Myth that the movie goes into production in January, and that it will be “different” from other DC projects.
Little else is known about the project, but it seems she has been instrumental in getting it off the ground.
Harley Quinn: Suicide Squad breakout character gets her own character
Suicide Squad was PG-13, whereas Birds of Prey is R-rated
The star had previously told Collider: “I pitched the idea of an R-rated girl gang film including Harley, because I was like, ‘Harley needs friends.’
“Harley loves interacting with people, so don’t ever make her do a standalone film.
“She’s got to be with other people, it should be a girl gang.”
She added: “I wasn’t seeing enough girl gangs on screen, especially in the action space. So that was always a big part of it.”
Robbie is on a career peak right now, after bagging an Oscar nomination for her role in I, Tonya – which she also produced.
Her latest movie Terminal, however, is picking up negative reviews – holding just 22% on Rotten Tomatoes.
Rolling Stone awarded zero stars, saying: “Zero stars, you read right! How did Vaughn Stein ever persuade Margot Robbie to star in a script that plays like something Quentin Tarantino upchucked after watching Blade Runner while reading Alice in Wonderland and ingesting too many hallucinogens?”
The movie goes into production next year
The 28-year-old is on top of her game
The Express, meanwhile, said: “The garish colours and fake sets make the film feel more like a cheap ’80s sitcom than hyper-stylised sci-fi.”
She will also shortly be seen in Mary Queen of Scots as Queen Elizabeth I, alongside Saoirse Ronan in the title role.
Robbie will also be in Once Upon a Time in Hollywood, reuniting with Leonardo DiCaprio.