The former Made In Chelsea star and her rapper beau - who married in September 2013 - made a cute twosome while posing for pictures before the event, which was held at Somerset House in London.
And, as always, our attention quickly turned to how fabulous Millie looked!
Despite being a Chelsea gal Mills proved she loves a high street buy too, rocking tailored shorts from Zara teamed with a matching blazer from New Look.
She also sported a striped tee from Sunspel and barely-there heels from River Island, adding a flourish of colour with a jewel-clad perspex clutch by Skinnydip London.
But our fave part of her look? Her adorable milkmaid braid!
Mills was clearly a big fan of it too, taking to Twitter earlier that day to say: "Morning! Thank @jjmakeup love my hair and make up"
In fact, we heart her chic hairdo so much, we can't wait to recreate it ourselves.
1. Millie went for a very smooth, polished look, so start by running a hair oil through freshly-washed damp locks to help smooth flyaways and give a healthy dose of shine. We like V05 Miracle Concentrate Elixir with Argan Oil, £5.19.
2. Once dry, create an off-centre parting before splitting your locks into two bunches at either side of your head, just below your ears.
3. Take one section and create a tight plait, then secure at the tips with a clear hair elastic. Repeat on the other side.
4. Grab one braid and fashion into a hairband by wrapping it around the top of your head, then fix it in place with bobby pins.
5. Do exactly the same with your opposite braid, then spritz a touch of hairspray (try John Frieda Frizz Ease Moisture Barrier Firm Hold Hairspray, £5.59) to help keep it all in place.
Make like Mills and team with flicked liner, feathery lashes and rosy lips (and a hot rapper hubby, if you happen to have one!)
What do you think of Millie's hair? Let us know by commenting below as the best comment across the site each week wins £50!
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