The actress is promoting Rouge Dior Nude Lipcolor in the advertisement, which features Portman lying topless on a sofa.
The collection includes a special hue, Grège #169, the proceeds of which will benefit Portman's chosen charity, the Free the Children Association.
The organisation helps to support girls' education in Kenya and Portman is currently an ambassador.
"I chose the colour Grège because it's the one I'd pick to wear myself," Portman said. "The number  contains different dates that are important to me and my family."
Portman, who became the face of Dior in 2010, criticised designer John Galliano last year after it emerged that he had made a series of racist remarks.
Galliano was later fired from the company.