The actress went for classic elegance, wearing an almost ankle-skimming black dress and cute bow-detail Chanel heels, as she joined the likes of Amy Willerton at the event.
But it was Keira's hair and make-up that really had us swooning.
Her skin was glowing with a very subtle apricot blush on the apples of her cheeks while her eyes looked like they'd been lined with black kohl with a wash of brown over the lids.
And her make-up artist - celebrity favourite Lisa Eldridge - later revealed what every beauty magpie wanted to know.
The lippy behind Keira's show-stopping pout! Lisa applied Chanel Rouge Allure Luminous Intense Lip Colour in Incandescente, £25, calling it a 'hot tomato red'.
Keira's pretty bouffant came courtesy of hairstylist Amiee Hershan who frequently works with the starlet.
She created a vintage-esque twisted updo which was carefully rolled up from the bottom, fastened into a bun and featured loose face-framing strands to keep it from looking too 'done.'
But we're not the only ones loving Keira's look.
TOWIE star Lauren Pope, who also owns her own hair extension brand, raved about Keira's hair and make-up choice on Twitter: 'Everything about this look is so pretty, the hair, the make up #keiraknightley #hairspiration #makeup #beauty.'
Red carpet perfection? Err, hell yes!
What do you think of Keira's latest look? Tell us below as the best comment from across the site each week wins £50!