The Black Swan star, who is the latest celebrity to put her face to the designer brand, admitted that she is still quite 'sloppy' when it comes to her own beauty regime.
Talking at a press conference, Parfums Christian Dior chief Claude Martinez called Portman 'charismatic and elegant', but the actress insisted, 'I'm pretty casual in my beauty routine in my real life. Some might say sloppy.'
The 29-year-old has already posed for promotional shots by Tim Walker, while Sofia Coppola recorded the TV adverts, which feature Portman cavorting with a young model.
She joked, 'I felt like a big old cougar. He's, like, 20. The commercial is subliminal advertising for my film.'