The actress walked the red carpet at the Odeon Kensington in London wearing a gorgeous Stella McCartney dress that featured a plunging neckline and bow design down the front.
A Little Chaos was directed by Alan Rickman and revolves around a female landscape gardener who is tasked with designing a fountain for Louis XIV at the Palace of Versailles.
It first premiered at the Toronto Film Festival last year.
In a recent interview with The Telegraph, director Alan praised Kate, saying: "She has a phenomenal listening. As a director you can put the camera on her doing nothing and it moves the film on. I couldn't have done it without someone I trust as much as Kate."
A Little Chaos is in cinemas 17 April.