As usual, Knightley got her hands on the most beautiful of designer gowns for the night and for once, she wasn't wearing Chanel Couture. Instead, she chose a midnight blue dress embroidered with a bird print from Valentino's Autumn/Winter 2014 collection.
It's hard to believe this Hollywood star, who is often kitted out in top-to-toe designer clothes, doesn't like the expensive lifestyle and was recently spotted sneaking a bottle of wine out of the pub where her husband James Righton was playing a gig.
Keira paired her Valentino design with smoky turquoise eyeshadow, a glossy curled hairstyle and Tiffany jewellery. She looked stunning - but the after-party required a change of outfit.
Like what you hear? Begin Again hits UK cinemas on 11th July.
See more of Keira's premiere style in her fashion evolution below. Yep, she used to look like this...