The 32-year-old actress wowed crowds at The Palais des Festivals as she twirled around in her plunging green Gucci gown (complete with super on-trend cape detail).
Lupita looked ethereal in the one-of-a-kind dress, which was adorned with hours worth of hand-embroidered crystals, beaded floral embellishments and silk flowers.
To compliment her dazzling gown, the 12 Years A Slave star swathed herself in glistening Chopard diamonds - including two adorable alice bands in her hair (we're sensing a trend here).
Lupita later revealed on Instagram that her hair style, created by hairstylist Vernon François, was inspired by "Uganda's women".
The Oscar winner was named as an ambassador for the beauty brand in April last year and has since lent her striking looks to a series of campaigns (she even named one of their eyeshadow palettes!).
It's going to be pretty hard to top this, guys.