The stunning actress was named number one in the poll of 2,500 people conducted by UK high street chain Superdrug.
Keira, 22, saw off stiff competition from actress-and-model Kelly Brook, supermodel Kate Moss and Spice Girl Victoria Beckham to finish top of the list.
Superdrug Beauty Director Katherine Le Clerc said: "The top 10 beauty icons list shows that today there is room for everyone's idea of true beauty.
"From the aloof glamour of Keira Knightley and Victoria Beckham's high-maintenance gloss to the fresh faced youthful looks of actress Gemma Atkinson."
Keira, who is the face of Chanel's Coco Mademoiselle perfume, regularly features on Hollywood's most sylist stars lists.
Kelly Brook - who finished second in the poll - wowed UK audiences with her impressive performances and style on TV talent show 'Strictly Come Dancing' in 2007. She has also designed lingerie and swimwear for UK high street store New Look
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