The singer opted for a 1950s style strapless red velvet dress with a gathered waist-band and full skirt.
The skirt was actually padded-out with layers of net petticoats, which you can just see peeking out from underneath the dress.
We think she looks like Elizabeth Taylor!
A jewelled box clutch, red platform court shoes and her trademark kooky nail art completed the look perfectly.
What do you think of Katy’s vintage style?