The former Made In Chelsea star attended a private preview of the Alexander McQueen Savage Beauty exhibition, which is currently showcasing the late designer's work at the Victoria and Albert Museum.
And dressed to impress for her stylish evening, Millie looked stunning in a floor-length silver-hued gown that featured a mega plunging neckline and revealing wrap skirt.
It also showed off her bronzed tan that no doubt was from her recent break in Marrakech.
Teaming her ensemble with nude barely-there sandals and a chic white box clutch, the pretty girl looked nothing short of exceptional.
But as well as her amazing attire, we were also pretty envious of her gorgeous hair and make-up.
Her tied back locks were completed with a super pretty fishtail braid – a 'do that we reckon is perfect for festivals. And you can pick up a similar-looking band from Vicky Pattison's VIP hair range for a reasonable £9.99.
Meanwhile, her make-up was also absolutely gorgeous. Millie worked glowy skin, soft shimmery taupe-hued peepers and a slick of mascara.
And if you want to copy Millie's dewy complexion, we can reveal the exact product behind it!
Make-up artist Nikki was behind the fashionista's look and took to Instagram to share a snap of her work, as well as naming Kevyn Aucoin's The Celestial Skin Liquid Lighing in Candelight (£42) as the secret behind Millie's subtle radiance.
The formula is a hybrid between a gel and creamy fluid, meaning it will glide and blend effortlessly on to skin.
You can either mix it with your foundation or moisturiser for an all-over glow, or use to highlight areas like you cheekbones, cupid's bow and brow bone. Just lightly pat it on to your desired spot for a stunning illuminated finish.
However, if you're on a budget, this number is pretty pricy! For a cheaper alternative, try NYX Liquid Illuminator, which gives a lovely gleaming finish and is just £7.