Charli XCX embraces ‘Brat Girl Summer’ in micro shorts as she parties with Anya Taylor-Joy and Rosalia at her star-studded birthday bash in LA

Charli XCX made sure all eyes were on her as she arrived at her lavish 31st birthday party at Tenants in Los Angeles on Saturday night.

The pop singer proved she was having a ‘Brat Girl Summer’ as she opted for a daring pair of micro shorts.

The British star, whose real name is Charlotte Aitchison, wore a black bra over a tight white cut-out T-shirt, which she paired with striking gray underwear.

Charli looked sharp for the festivities in a pair of black knee-high boots, accessorizing with a matching handbag and sunglasses.

She is credited with starting the ‘Brat Summer’ movement – named after her album Brat – which launched a trend characterised by partying and being completely yourself.

Charli XCX made sure all eyes were on her as she arrived at her lavish 31st birthday party at Tenants in Los Angeles on Saturday night

She was joined at the star-studded event by a number of pals, including Anya Taylor-Joy, who looked stunning in a black plunging neckline dress

She was joined at the star-studded event by a number of pals, including Anya Taylor-Joy, who looked stunning in a black plunging neckline dress

Meanwhile, Rosalia showed off her incredible figure in a black bralette and matching shorts

Meanwhile, Rosalia showed off her incredible figure in a black bralette and matching shorts

Charli was joined at the star-studded event by a number of girlfriends, including Anya Taylor-Joy, who looked stunning in a black plunging dress.

The actress turned heads in a tight-fitting, floor-length strappy dress.

She looked even taller with a pair of sky-high heels and accessorized with two long gold chains.

Meanwhile, Rosalia showed off her incredible figure in a daring black bralette and matching shorts.

The singer added some glam to her outfit with a pair of stunning silver knee-high boots and completed her look with a gray baseball cap.

Rosalia seemed in good spirits as she arrived with a large bouquet of flowers for the birthday girl.

Meanwhile, Addison Rae looked very tall in blue jeans and a colorful strappy tank top.

The actress and influencer wore her long, dark locks loose and donned a stylish pair of glasses as she arrived at the party.

Addison accentuated her figure with a pair of high black sandals and opted for a simple gold necklace.

The pop singer proved she was having a 'Brat Girl Summer' when she traded in her pants for tiny micro shorts

The pop singer proved she was having a ‘Brat Girl Summer’ when she traded in her pants for tiny micro shorts

The British star, whose full name is Charlotte Aitchison, showed off a black bra through a tight white cut-out T-shirt, which she paired with striking gray underwear

The British star, whose full name is Charlotte Aitchison, showed off a black bra through a tight white cut-out T-shirt, which she paired with striking gray underwear

Charli stepped out for the festivities in a tall, lanky style in a pair of black knee-high boots, accessorizing with a matching handbag and sunglasses.

Charli stepped out for the festivities in a tall, lanky style in a pair of black knee-high boots, accessorizing with a matching handbag and sunglasses.

Anya turned heads in her strappy figure-hugging number that fell to the floor

Anya turned heads in her strappy figure-hugging number that fell to the floor

She added inches to her frame in a pair of sky-high heels and accessorized with two long gold chains

She added inches to her frame in a pair of sky-high heels and accessorized with two long gold chains

Singer Rosalia added some glamour to her ensemble with a pair of stunning silver knee-high boots

Singer Rosalia added some glamour to her ensemble with a pair of stunning silver knee-high boots

She kept it understated by wearing a gray patterned baseball cap

She kept it understated by wearing a gray patterned baseball cap

Rosalia seemed in a good mood as she arrived with a large bouquet of flowers for the birthday girl

Rosalia seemed in a good mood as she arrived with a large bouquet of flowers for the birthday girl

Scout Willis cut a tall, lanky figure in a brown miniskirt and blue blouse as she arrived at the party

Scout Willis cut a tall, lanky figure in a brown miniskirt and blue blouse as she arrived at the party

Demi Moore and Bruce Willis' daughter smiled as she waved to the cameras

Demi Moore and Bruce Willis’ daughter smiled as she waved to the cameras

Kylie Jenner’s best friend Anastasia ‘Stassie’ Karanikolaou looked absolutely sensational as she went braless under a plunging black backless crop top.

The influencer paired the daring, sparkly top with cropped shorts and chunky, knee-high boots.

Stassie couldn’t believe her luck when she was spotted climbing into a waiting vehicle at the end of the evening.

Charli is celebrating her birthday after confirming her fans’ suspicions about a collaboration with pop star Billie Eilish.

She did so by sharing a sneak peek of the new song on Instagram, just hours before its release.

Charli caused an online stir after sharing a mysterious photo that showed only two bodies, with their heads out of the frame.

After fans were asked if they could predict who would be the featured guest on the upcoming remix of her track Guess, taken from her sixth studio album, Brat, social media users were quickly convinced they had discovered the identity of her newest collaborator.

And it looks like they got it right, because Charli confirmed that the duo’s collaboration will be released on Thursday at 6pm EST (11pm in the UK).

Meanwhile, Addison Rae had a very long show in a pair of blue denim shorts and a colorful strappy tank top

Meanwhile, Addison Rae had a very long show in a pair of blue denim shorts and a colorful strappy tank top

The actress and influencer let her long dark locks loose and donned a stylish pair of glasses as she arrived at the party

The actress and influencer let her long dark locks loose and donned a stylish pair of glasses as she arrived at the party

The beauty showed off her gorgeous smile and opted for a simple gold chain

Addison slipped her phone into the back pocket of her cut-out jeans

The beauty showed off her gorgeous smile and opted for a simple gold chain

Addison lifted her figure in a pair of sky-high black sandals

Addison lifted her figure in a pair of sky-high black sandals

Kylie Jenner's best friend Anastasia 'Stassie' Karanikolaou looked absolutely sensational as she went braless under a plunging black backless crop top

Kylie Jenner’s best friend Anastasia ‘Stassie’ Karanikolaou looked absolutely sensational as she went braless under a plunging black backless crop top

The influencer paired the daring glitter top with shorts and chunky over-the-knee boots

The influencer paired the daring glitter top with shorts and chunky over-the-knee boots

Stassie was all smiles when she was spotted climbing into a waiting vehicle at the end of the evening

Stassie was all smiles when she was spotted climbing into a waiting vehicle at the end of the evening

As the sneak peek began, Charli donned her signature black sunglasses for a close-up shot and asked the camera, “Hey Billie, are you there?”

Then a portion of the song played, with the final frame showing Charli and Billie collapsed on a pile of underwear, a reference to the lyrics of the song ‘You want to guess the colour of my underwear’.

Charli confirmed it in the caption, “Guess with Billie Eilish – Out at 6pm EST.”

Charli XCX is already in the spotlight after her hyperpop-electronic record BRAT debuted as “the most critically acclaimed album of the year,” surpassing Beyoncé’s latest album, Cowboy Carter, and Taylor Swift’s The Tortured Poets Department.

Charli’s new album BRAT has reached number one on Metacritic, surpassing Queen B’s country-pop album Cowboy Carter, which was released on March 29 and marks the singer’s eighth studio album.

According to review aggregator Metacritic, the film received “universal acclaim” based on a score of 92 out of 100, based on the scores of 11 critics.

BRAT is the singer’s sixth studio album and is said to evoke the illegal rave scene in London, where Charli began performing when she was 14 or 15.

According to Charli XCX, BRAT is her “most aggressive and confrontational record,” but also her most vulnerable.