The actress shared a photo of her new platinum 'do on her WhoSay page, writing, "In Cannes with The Honourable Woman. I'm blonde btw...@mariesalon."
In the pic, the 36-year-old beauty showed off her blonde tresses as she soaked up the sun in the French Riviera. She sported a simple white T-shirt and oversized tortoiseshell sunnies.
This isn't the first time Maggie has experimented with her hair color. She also went blonde for her role in the award-winning drama, "Sherrybaby," back in 2006.
We think she looks younger with her new 'do, but what do you think of her platinum strands? Tell toofab in the comment section below, and click "Launch Gallery" below to see more stars who've gone from brunette to blonde.