The Australian performer played the comic book favourite in Suicide Squad, becoming a strongly-reviewed element of an otherwise lambasted movie.
Speaking to Variety in a video shared on Twitter, she said it was a fondness for one particular project from director David Ayer that won her over.
“End Of Watch was one of my favourite films and the reason I signed on for Suicide Squad,” she said.
“It was because I loved End of Watch so much and I saw it about four times in the cinema.”
Robbie also spoke about how much fun she’s had in the part, saying: “Harley’s one of those, you know, insane characters.
“And people do seem to really like her, so I hope I get to keep playing her.
“But it’s so nice, like, right now I’m working on an indie film that we’re producing as well, and it’s a six million dollar film and I love it so much but the idea that I get to do that and then walk onto a hundred-million dollar film set with pyrotechnics and all that crazy stuff and like, have my baseball bat and just do a totally different thing is just…”
“Amazing,” her interviewer Jake Gyllenhaal added.
It was announced back in 2016 that Warner Bros wants to plan a film focussing on Harley Quinn, while Ayer is also back to direct and produce Gotham City Sirens.
A sequel to Suicide Squad is also believed to be wanted.
Robbie is currently promoting I, Tonya; which is in awards season contention and will be released in the UK on February 23 in the UK.