CANNES, France – Sienna Miller is on a roll.

The actress is capping off her comeback year with a stint on the jury of the Cannes Film Festival, where she joins a motley crew including Jake Gyllenhaal, Rossy de Palma, Sophie Marceau and jury presidents Joel and Ethan Coen.

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Sitting in a seafront suite at the Carlton hotel, she muses about the implications of deciding the fate of some of the world’s top filmmakers.

“I don’t feel worthy of judging these films. I will say what I thought was brilliant and be supportive. It’s a huge responsibility because, of course, whoever wins these prizes, you know, their life is transformed, so I definitely feel the weight of it,” she says.

For the female jury members, the festival carries another kind of weight: Showing up with a trunk full of red carpet stunners. Miller has enlisted stylist Kate Young to help with the mammoth task.

“I have a really strong sense of what I like and I think she’s amazing,” she says. “You have to bring it, because it’s Cannes. You can’t be in your pajamas, although I did ‘pajama’ it this morning to the 8.30 a.m. screening and got away with it,” she adds with a smirk.

For the opening ceremony, Miller picked a midnight blue Lanvin dress accessorized with Atelier Swarovski jewels — a case of happy synergy, since Swarovski is supporting the current Jeanne Lanvin retrospective at the Palais Galliera museum in Paris.

She traces her friendship with the crystal-maker back to the Twenty8Twelve fashion brand she used to design with her sister, Savannah.

“I’ve worked with them for years as a designer and worn it as an actress and as myself. The pieces are beautiful and versatile and classic, and simple but edgy,” says Miller, decked out for the interview in a black Stella McCartney jumpsuit, Joie a la Plage sandals and metallic gray Atelier Swarovski jewelry.

Her style hasn’t always been so clean-cut, though she downplays her transformation from poster girl for boho style to paragon of minimal chic. “I think I got a haircut, and that was it,” she says with a shrug.

“I used to be like a Christmas tree, kind of with belts and jewelry everywhere, and I think you grow up and you become a little bit more sophisticated maybe, but I don’t feel like I’m suddenly wearing clothes that I’ve been put in. It’s a collaboration and it’s things that I’m drawn to,” she insists.

The 33-year-old credits her changing looks and career evolution to growing up and having Marlowe, her daughter with fiancé Tom Sturridge.

“I took time off and had a child and was a mother, and then that made me reevaluate my priorities and the kind of work that I wanted to do, and if I was going to work – which means time away from my child – it had to be something that I was going to really give my heart to,” she says.

“I think I just reevaluated my choices and worked harder and became more focused, and just more responsible as a human, as you do when you turn 30 and have a child. But yeah, I’m definitely working with people that I hadn’t worked with before and I do feel like I’m in a different place in my career, and it’s all good,” she adds.

A tabloid fixture in her 20s, thanks to her on-off relationship with Jude Law, Miller is enjoying the range that comes with a lower public profile. It allowed her to deliver critically acclaimed performances last year in “Foxcatcher” and “American Sniper,” as well as her recent turn as Sally Bowles on Broadway in “Cabaret” opposite Alan Cumming.

“I do feel like it’s pretty impossible to do that if you have the level of attention that I used to have, so I deliberately disappeared,” she explains. “I don’t think people have such a strong kind of opinion anymore, which has been really beneficial.”

Miller will be reunited with her “American Sniper” costar Bradley Cooper later this year in “Adam Jones,” in which they both play chefs. Research for the role involved a stint in the kitchen of Marcus Wareing, a two-star Michelin chef in London.

“Look, I’ve still got burns and scars,” she says, proffering an arm. “I think I cooked maybe 500 pieces of turbot. I can cook fish exquisitely now. But we were working in a live kitchen for two weeks, and I was on the station and the heat is about 117 degrees, and you have hot oil spitting in your face.”

Even worse, Cooper was constantly screaming at her.

“We literally came off  ‘American Sniper’ and went straight onto that together, so we did two back-to-back. And having had him with this thick Texan accent and being like, ‘I love you,’ he was like throwing pans at my head. I was like, ‘Yes, chef! Yes, chef!’ You just think, ‘What is this job?’ It’s the weirdest thing,” she says with a laugh.