The 20-year-old model was effortlessly glamorous yesterday (9 July), as she headed to The Animal Ball charity event in London with her sibling and wore a long black gown, which accentuated her slim figure, with a pair of chunky black boots and the strange face accessory.
Perhaps taking a leaf out of Justin Bieber's book - since he was seen wearing a bizarre black gas mask on more than one occasion in the UK this year - Cara covered her striking facial features with the black mask, which appeared to be made out of woven leather and was secured in place at the back with a buckle.
She then added another weird accessory to her ensemble, by holding what looked like a black leather truncheon.
Meanwhile, her older sister Poppy donned an eye-catching gold dress with a gorgeous intricate print and matching gold heels.
Given that the charity bash - held at Lancaster House at St James Palace - had a mask theme, Poppy was seen holding her own large and elaborate gold creation. We can imagine that looked pretty epic teamed with her frock!
The two girls were dressed up for good reason, since they rubbed shoulders with some rather important members of society at the ball, most notably Prince Charles and Camilla, who also donned masks for the occasion.
In fact, Cara was even said to have had a giggle with Prince Charles after asking him whether he had any tattoos!
Whose outfit do you prefer: Cara or Poppy's? Let us know below!