Her scraped back do looked sleek, stylish and not at all over the top as she kept the rest of her outfit simple in a plain LBD. If anyone knows how to rock the red carpet, it's Sienna.
Let us know how you rate her look and take a look below to see her finest fashion moments to date.
The Perfect 10: Sienna MillerIs this Sienna's best red carpet moment to date? She looks stunning in a backless Matthew Williamson gown at the Baftas 2007. The Perfect 10: Sienna Miller The Factory Girl opted for another backless number at the 2008 Bafta Awards. This time she opted for a slinky Dior gown and Chopard jewels. The Perfect 10: Sienna Miller Sienna Miller wows in red at the Valentino 45th Anniversary celebration, back in July 2007. She opted for a spectacular Valentino gown, of course. The Perfect 10: Sienna Miller The Layer Cake actress looked pretty in pink in this strapless number at the Montblanc Signature for Good Charity event in 2009. The Perfect 10: Sienna Miller She wore her favourite designer, Matthew Williamson, to pick up her award for Elle Style Icon in 2009. The Perfect 10: Sienna Miller The perfect LBD! Miller looks radiant on the red carpet at the opening of the House of Esquire in LA. The Perfect 10: Sienna Miller The star of GI Joe arrives at a screening for the movie in LA. Sienna oozed Hollywood glamour in this gold gown teamed with ruby red lips and curled locks. The Perfect 10: Sienna Miller Sienna sparkled in a Swarovski embellished mini dress from her own Twenty8Twelve collection to the 2009 MTV Movie Awards. The Perfect 10: Sienna Miller Sienna Miller on the red carpet with Jude Law at the 2010 MET Ball. Sienna dazzled in a low-cut Pucci gown. The Perfect 10: Sienna Miller The Alfie star looked gorgeous in a nude, Stella McCartney gown at the Unesco Charity Gala in October 2010. She can't keep away from that red lipstick! The Perfect 10: Sienna Miller