Millie Bobby Brown is changing up her look, adopting fresh fashion to complement her newly bleached hair.

The Stranger Things sensation turned 21 on February 19, shocking fans with how young she still is, despite appearing much more mature.

Now, in her latest Instagram posts, the British actress — who has been promoting new film The Electric State — slipped into fun and flirty looks calling back to the Y2K era.

Posing on a balcony overlooking the hills, Brown stunned in a cropped white shirt, revealing her washboard abs.

She teamed the bright look — which was styled by Ryan Young — with a pair of ombre blue and white pants, which were embellished with swirled stones and beading. 

In the comments, fans drew comparisons to a young Britney Spears, Barbie, and Elsa from the animated movie Frozen.

Millie Bobby Brown is changing up her look, adopting fresh fashion to complement her newly bleached hair

In one of her latest Instagram posts, the British actress slipped into a fun and flirty look calling back to the Y2K era

In some snapsH๏τs, Millie donned a plush ivory fur coat to add another dynamic to her eye-catching ensemble.

And the superstar, who married Jon Bon Jovi’s son Jake Bongiovi last year, flaunted an almond-shaped French manicure.

Read More Millie Bobby Brown rocks sparkly bustier and new blonde hair as she rings in her 21st birthday

Her bright blonde hair was parted down the middle and styled in tousled layers that fell over her chest.

She took the look up a notch with a glowy makeup application that included glossy pink lips.

Fans were left stunned over the star’s real age after they claimed she looked a ‘decade older’ at the SAG Awards over the weekend.

One social media user wrote on X, ‘Literally had to double check it was her who turned 21 the other day and not 40.’

‘When did 21 going on 45 looks become fashionable?’ asked another, while someone else added she’s ‘already looking like 30-year-old.’

Others were simply blown away by the pᴀssage of time, given that Millie was just 12 when she made her debut as Eleven on Stranger Things in 2016.

‘Stunning,’ one person weighed in. ‘It’s weird watching them grow up before our eyes. I don’t think I’ll ever get used to it.’ 

Posing on a balcony overlooking the hills, Brown stunned in a cropped white shirt, revealing her washboard abs

On Monday she wore a blue and white striped co-ord, adding a shrunken white shrug and white heels

The Barbie-inspired look was reminiscent of something Cher might’ve worn in the movie Clueless

She looked much older on Monday when with husband Jake Bongiovi at the after party for the World Premiere of Netflix’s The Electric State at Citizen News in Los Angeles

In an Instagram post shared on Monday, the former child star wore a blue and white striped co-ord, adding a shrunken white shrug and white heels.

The Barbie-inspired look was reminiscent of something Alicia Silverstone’s beloved character Cher might’ve worn in the movie Clueless.

Millie used geometric turquoise, yellow, and pink digital stickers for one flick, including a tag that read, ’90’s.’

She sported frosty blue eyeshadow, shimmery ɴuᴅᴇ lipstick with brown lip liner, and accented the look with white-framed sunglᴀsses.

And the new wife proudly flaunted her huge diamond wedding ring while toting a white leather Versace purse.