The 27-year-old model was definitely channeling her inner Monroe (the white faux fur bolero, the glossy bouffant do, the plum lipstick) at the London event. She also took the opportunity to style out a silk négligée from her Rosie for Autograph sleepwear collection (£89).
This is how to take luxe loungewear outside of the boudoir.
Cast your mind back to the Louis Vuitton Autumn/Winter 2013 catwalk collection - the one where Marc Jacobs sent his model fleet, including Kate Moss, down the runway in slinky silk nightdresses, fur coats and greasy bed-head hair. That's when négligées became a serious fashion thing.
Rosie's look doesn't quite have that edge (no scowl, no cigarette in hand) but the Devon-born beauty looked beautiful. The results being more Hollywood glam and less grungy girl in nightdress and biker boots.
And yes, the Rosie for Autograph Eau De Parfum is the perfect scent to wear when you're doing this trend.
"As with my lingerie collection, I was drawn to the elegance and simplicity of the centifolia rose used in the fragrance," Rosie said in a statement ahead of the launch.
"A rare, vintage style flower, which feels luxurious and sexy when worn".
LOVE ROSIE'S STYLE? Flick through this gallery to see more great looks from the model lady.