The Girls Aloud singer reveals she thinks the 'Rude Boy' hitmaker's dress sense is to be admired, as she embraces her curvaceous figure with everything she wears.
She explained: "Rihanna is my style icon - she's got such a great figure, all curves. It's so nice to see that in an industry where curves are few and far between. Best of all, she's not afraid to show them off! We should embrace our curves and enjoy looking like women."
The blonde beauty - who is currently taking a hiatus from her music career to concentrate on acting - admits while she opts for a glamorous look on the red carpet, she prefers to slouch around in her leggings at home.
She said: "Leggings are my fashion weakness - even though they're so overdone. It's a form of fashion laziness and I can't seem to stop wearing them! I wear them at home with a slouchy vest."
Sarah, 28, also reveals she is pleased many trends have now gone "full circle", she has had some fashion disasters in the past.
She added to heat magazine: "Vivienne Westwood is my favourite designer. Everyone's gone full circle right now - her collection's gone back to the '80s and I love it.
"At some point, whether you do what we do or not, you're always going to look back and go, 'Oh my God, I can't believe I wore that!' "