Millie Bobby Brown Building Sandcastles In Cheeky Bikini Shows Her 'Birthday Magic'

Millie Bobby Brown is layering on the swimwear action as she celebrates her birthday. The British actress hit the big "21" this weekend, ushering in a new year with a bikini selfie shared on husband Jake Bongiovi's Instagram. Posting to her own feed on Saturday night, Millie sizzled in an unbelievably cheeky swimsuit, flaunting her killer figure in the sun as she enjoyed a day at the beach. Showing off her curves and the sandcastles she'd built, Millie also snuck in a bombshell sunbathing snap, and the whole thing earned her over 1 million likes in just three hours.

Scroll for the photos. Showing off her fun side in her opening slide, Millie joined some girlfriends on the beach, with everyone posing around some sandcastles.

Hinting at her curves in a barely visible bikini highlighting her cleavage, the Stranger Things star smiled for the camera, posing on all fours in shades and backed by ocean waters. Tagging herself in Turks and Caicos, Millie drove fans to swipe, where she wowed in a butt-baring red thong bikini while overlooking the water from a boat.

Displaying her peachy rear and toned legs, Millie reminded her 63 million+ followers of her incredible silhouette, one she flaunted in her final slide for a show-stopping sunbathing photo. Here, the Florence by Mills founder lounged around on her back and from a beach hammock while reading a copy of Vanity Fair. Rocking a triangle bikini with red piping and tiny black briefs, Millie sizzled with an ab flash, also showcasing her toned, tan legs as she wowed in tropical chill mode.

In a caption, she wrote: "Birthday magic." Quick to reply, one fan called Millie a "real-life Barbie."

Millie had already made 2025 headlines with this swimsuit selfie, posted on her Instagram last month. Snapping a photo from a boat, she stunned in a stitched yellow bikini with a deep neckline, highlighting her firm abs and curvy hips while enjoying a day on the water.

"So I like to go to the gym. I do Thai boxing Mondays, jujitsu Tuesdays and Thursdays, and Wednesdays I do boxing with Mark. He was a world champion at one point. I absolutely love it," she's stated while discussing her varied workout routine.

"I train to box. Obviously I don’t want to do it professionally. But I have done some inter-clubs before. It’s at Phoenix MMA U.K., down in London. It’s a great gym, and I have lots of friends," she continued.

The above photo, meanwhile, promoted Millie Bobby Brown's Florence by Mills Fashion line, launched last year. Snapping a selfie in tight denim shorts, the A-lister wowed in a skimpy white cami top, peeping her toned tummy as she plugged her fast-rising label.