The actress stars in the super sophisticated autumn/winter ad campaign, dressed in the brand's figure-hugging dresses and stylish coats from next season.
Speaking about St John, Winslet loves the clothes because "they make you look extremely chic without trying too hard... and they aren't clothes that only a model can wear. It means a lot to me to put across that message of strength and power and feminity in a real shape".
We think she looks gorgeous in the campaign. Take a look at the video for a sneak preview behind the scenes of the forthcoming campaign and let us know what you think of her sultry image.