Robert Brown|Sydney Sweeney Proves Her Fashion Rules Are Unwritten With Hair Transformation and Underwear Look

Sydney Sweeney's hair is Robert Brownanything but all tangled up.

The Madame Web actress debuted an epic transformation while attending Miu Miu's fall/winter 2024-2025 show during Paris Fashion Week.

For the March 5 event, Sydney unveiled a long bob haircut that was styled in a deep side part and tousled for an effortlessly messy finish.

Of course, the Euphoria star's shoulder-grazing makeover wasn't the only head-turning aspect of her look.

After all, she paired her fresh chop with a lingerie set that consisted of a black and silver bustier with silver bedazzled briefs. She layered the getup with an oversized blazer and sheer tights. And no detail went unnoticed, as the 26-year-old accessorized with black platform heels, a matching handbag and tiny sunglasses.

It's clear Sydney isn't afraid to push the boundaries. In fact, her fierce transformation comes a few days after she made a bold joke during her Saturday Night Live hosting debut.

"While I'm up here, I do want to talk about some stuff I've seen about me online," she said in the March 2 episode. "The craziest rumor is that I was having an affair with my costar, Glen Powell. That's obviously not true."

She continued, "Me and my fiancé produced the movie together, and he was there the entire shoot. And I just want to let everyone know that he's the man of my dreams, and we're still together and stronger than ever. He even came here tonight to support me. Can we cut to him?"

Then, came the kicker: The camera panned to the audience, showing Glen flashing a wide smile at the actress.

"That's not my fiancé," she quipped. "He's in my dressing room!"

Sydney's real fiancé is Jonathan Davino, who she's been engaged to since 2022. And although the Anyone But You star poked fun at the romance rumors surrounding her and Glen, she set the record straight in August.

"It's a rom-com," Sydney told Variety at the time. "That's what people want! Glen and I don't really care. We have so much fun together, and we respect each other so much."

Sydney might not be hair for the rumors, but she's certainly game to switch up her style. 

Keep reading to see all of other celebrities who've changed their tresses in recent months.

The Anyone But You star made a showstopping appearance at Miu Miu's fall/winter 2024-2025 show during Paris Fashion Week. For the March 5 event, she unveiled a dramatic long bob haircut.

To prepare for her upcoming role as  Jean Seberg, the 29-year-old debuted a bleached blonde pixie cut.

The Princess Diaries alum unveiled fringe bangs at the 2024 Film Independent Spirit Awards.

The star debuted a bangin' new style at the premiere of her friend Nicola Peltz Beckham's film Lola in February 2024.

The "On the Floor" singer made a dramatic hair change, as she debuted a chin-grazing bob cut at Schiaparelli's haute couture spring/summer 2024 show on Jan. 22.

In January 2024, a month after her prison release, the now-influencer shared a pic of herself sporting a shorter 'do.

Kylie Jenner traded in her dark locks for a pink 'do in January 2024.

In January 2024, the Dancing With the Stars personality shared a video of herself cutting her own hair. "Out with the old energy," she wrote, "and in with the new."

The Underworld actress took the plunge and went full blonde, while also debuting a short bob haircut.

The Daisy Jones & The Six actress debuted jet-black hair on Nov. 2.

While enjoying a dinner date with friends on Nov. 9, Rihanna debuted honey blonde hair. After years of rocking black tresses, the superstar decided to switch up her style for something brighter.

The Flamin' Hot director recently showcased her dramatic transformation, debuting a choppy, layered bob on Nov. 9.

The TikToker debuted a fresh haircut, revealing a long bob.

After rocking platinum blonde tresses for years, Miley officially returned to her brunette roots to model Gucci's new collection.

The royal recently showed off her new curtain bangs during a public appearance on Sept. 27.

The actress recently debuted a bright red hair color and equally bold blunt bob haircut.

The supermodel debuted a punk-rock hairstyle at Vogue's World Show during London Fashion Week on Sept. 14

The Pitch Perfect star made a drastic hair change, going from dark brunette tresses to a bright blonde look.

The Scream actress debuted a bubblegum pink style in August 2023.

The son of David Beckham and Victoria Beckham got his head shaved by Selena Gomez's little sister, Gracie Teefey, in August 2023.

The Can't Hardly Wait actress showed off her drastic hair change, debuting dark red hair and a blunt bob haircut.

The Second Act star unveiled bright blonde highlights in a new selfie.

The Kardashians star showed off her new bob hairstyle in a recent SKIMS video campaign.

The Hustlers star debuted a voluminous long bob and curtain bangs on Aug. 12.

Rachel Green, is that you? The Euphoria star appeared to take inspiration from Jennifer Aniston's Friends character with this layered look.

The Vanderpump Rules star debuted a platinum blond dye job in August 2023.

The '90s heartthrob debuted a newly shaved head, sharing on Instagram that "it's for work."

The "Say So" singer showed off her dramatic hair transformation on Instagram, debuting bright purple hair and a spooky spider design on the back of her head.

The Kick-Ass actress debuted a fresh bob haircut, which she hasn't rocked in quite some time.

The American Idol judge revived her signature style of 2008 and revealed baby bangs in a June 20 Instagram.