"It was decided on Monday night that she could come to Cannes, and she got on the next plane to arrive just in time to get dressed and come to our premiere," said a rep for Wendy and Lucy. "She came in and had a long nap and then came to the screening."
Williams, 27, was radiant in a vintage Chanel Haute Couture dress. She will remain in Cannes at least through Friday night to promote another festival movie in which she appears, Synecdoche, New York, before flying back to the United States to resume filming a Martin Scorsese movie in Boston.
Williams has kept a low profile since Ledger died last January at age 28 of an accidental overdose. After attending his memorial service in Australia, she has spent time with their 2-year-old daughter Matilda in New York and on the set of her new film.
At Cannes, Williams's work in Wendy and Lucy was well-received, the rep says.
"Some people said tonight it was a transcendent performance," he says. "It's about things going on around her and she's just she's trying to go forward and things are not working out for her. You see her taking care of herself first [in the film], which is exactly what we must do."