The Australian star wore a black feathered asymmetric crop top with a long black skirt for the red carpet event at the BFI Imax.
She finished off the look with a pair of bright pink gloves.
At the event Robbie, who has previously admitted to being an unlikely Love Island fan, shared a laugh with 2019’s stars Michael Griffiths, Jordan Hames and Lucie Donlan before going inside.
The trio matched Robbie’s outfit in their all-black looks as they chatted away at the premiere.
Robbie’s co-stars Rosie Perez, Jurne Smollett-Bell, Mary Elizabeth Winstead, Ella Jay Basco and Chris Messina also joined the star to pose for pictures ahead of the movie screening.
The film sees Robbie reprise her role as Harley Quinn after winning over audiences in 2016’s Suicide Squad.
The spin-off movie, directed by Cathy Yan, sees Harley team up with a new all-female gang – including Huntress (Winstead), Black Canary (Smollett-Bell) and Renee Montoya (Perez) in order to save a young girl from crime lord Black Mask (played by Ewan McGregor).
The actress is also expected to appear in the sequel to Suicide Squad, which is slated for release in August 2021.
Robbie is set to attend the Baftas on Sunday, after landing a shock double nomination in the Best Supporting Actress category.
The star received nods for her roles as a fictional Fox News journalist in Bombshell and as Sharon Tate in Quentin Tarantino’s Once Upon A Time… In Hollywood.
She will go up against Scarlett Johansson (Jojo Rabbit), Florence Pugh (Little Women) and Laura Dern (Marriage Story).
Birds of Prey is out in UK cinemas from February 7.