Billie Eilish 21 kisses boyfriend Jesse Rutherford 31 at their

Billie Eilish, 21, kisses boyfriend Jesse Rutherford, 31, at their star-studded birthday party in LA

Billie Eilish got into the festive spirit as she slipped into a sexy Mrs. Claus costume to celebrate her 21st birthday, joined by boyfriend Jesse Rutherford, former celebrity crush Justin Bieber and his supermodel wife Hailey.

Arriving at her party in a bright red sleigh alongside a friend with a champagne flute, the Bad Guy singer looked happy as she arrived at The Edition in West Hollywood with an unidentified pal on Saturday night.

Once inside, the seven-time Grammy winner packed the PDA with her boyfriend, 31, who couldn’t keep his hands off her as they kissed on the dance floor before her loved ones gathered to sing her Happy Birthday.

In love: Billie Eilish got into the festive spirit as she slipped into a sexy Mrs. Claus costume to celebrate her 21st birthday, joined by boyfriend Jesse Rutherford, former celebrity crush Justin Bieber and his supermodel wife Hailey

In love: Billie Eilish got into the festive spirit as she slipped into a sexy Mrs. Claus costume to celebrate her 21st birthday, joined by boyfriend Jesse Rutherford, former celebrity crush Justin Bieber and his supermodel wife Hailey

When a DJ urged her friends and family to “put their friggin’ hands up for Billie” and “make some noise,” the lead singer of rock band The Neighborhood wrapped his arms around her shoulders.

As the crowd sang and presented her with a beautiful birthday cake, the Gen Z superstar beamed alongside her husband, glancing fondly at her as she prepared to blow out her candles, and rapper Doja Cat.

Rutherford rocked a seasonal Santa suit coordinated with Eilish’s skimpy Mrs. Claus outfit, which consisted of a faux fur-trimmed mini dress, matching elbow-length gloves, a black belt and large silver hoop earrings.

As the Oscar-winner’s guests serenaded her, she happily held up one of her first legal drinks alongside some of Hollywood’s biggest celebrities.

Birthday girl: Arriving at her party in a bright red sleigh alongside a friend with a champagne flute, the Bad Guy singer looked happy as she arrived at The Edition in West Hollywood with an unidentified pal on Saturday night

Birthday girl: Arriving at her party in a bright red sleigh alongside a friend with a champagne flute, the Bad Guy singer looked happy as she arrived at The Edition in West Hollywood with an unidentified pal on Saturday night

Dancing Queen: Once inside, the seven-time Grammy winner grabbed the PDA with her boyfriend, 31, who couldn't keep his hands off her as they kissed on the dance floor before her loved ones gathered to sing her happy birthday

Dancing Queen: Once inside, the seven-time Grammy winner grabbed the PDA with her boyfriend, 31, who couldn’t keep his hands off her as they kissed on the dance floor before her loved ones gathered to sing her happy birthday

Cozy: When a DJ urged her friends and family to put their

Cozy: When a DJ urged her friends and family to put their “motherf**king hands up in the sky for Billie” and “make some noise,” the lead singer of rock band The Neighborhood kept his arms wrapped around her shoulders

Attendees also included Kendall Jenner, Olivia Rodrigo, pop punk princess Avril Lavigne, Dove Cameron, Eiza Gonzalez, drummer Gethin Davies and more.

Jenner, 27, and Hailey Bieber, 26, appeared to be having a blast at the event as they playfully posed with middle fingers in a photo booth.

Kendall also posted some sultry sepia snaps of herself on Sunday, capping a busy weekend for the supermodel as she celebrated her nephew Mason’s epic 13th birthday earlier in the evening.

Delicious!  As the crowd sang and presented her with a beautiful birthday cake, the Gen Z superstar beamed alongside her husband, glancing fondly at her as she prepared to blow out her candles, and rapper Doja Cat

Delicious! As the crowd sang and presented her with a beautiful birthday cake, the Gen Z superstar beamed alongside her husband, glancing fondly at her as she prepared to blow out her candles, and rapper Doja Cat

Coordination: Rutherford rocked a seasonal Santa suit that coordinated with Eilish's skimpy Mrs. Claus outfit, which consisted of a faux fur-trimmed mini dress, matching elbow-length gloves, a black belt and large silver hoop earrings

Coordination: Rutherford rocked a seasonal Santa suit that coordinated with Eilish’s skimpy Mrs. Claus outfit, which consisted of a faux fur-trimmed mini dress, matching elbow-length gloves, a black belt and large silver hoop earrings

Twenty fun!  As the Oscar-winner's guests serenaded her, she happily held up one of her first legal drinks alongside some of Hollywood's biggest celebrities

Twenty fun! As the Oscar-winner’s guests serenaded her, she happily held up one of her first legal drinks alongside some of Hollywood’s biggest celebrities

The models also took photos with Jesse Jo Stark, 31, which showed her with a cheesy grin, tongue out and lips painted.

Eilish’s party followed her Friday night performance at the Kia Forum in Ingelwood, California, where the singing sensation was treated to a cake by her close family and new boyfriend Jesse Rutherford, 31, onstage.

“Do you want to take pictures?” Billie joked off stage. “Give me two days. I’ll be 21 in two days, it’s fucking amazing.”

Life at the party: Attendees also included Kendall Jenner, Olivia Rodrigo, pop punk princess Avril Lavigne, Dove Cameron, Eiza Gonzalez, drummer Gethin Davies and more

Life at the party: Attendees also included Kendall Jenner, Olivia Rodrigo, pop punk princess Avril Lavigne, Dove Cameron, Eiza Gonzalez, drummer Gethin Davies and more

Cheers: Everyone at the party raised their glasses to the birthday boy

Cheers: Everyone at the party raised their glasses to the birthday boy

Letting go at her party, Eilish didn’t shy away from getting involved in a PDA with her boyfriend after years of keeping previous romances with Matthew Vorce, Brandon Que and Henry Whitford out of the spotlight.

Earlier this month, she revealed in an interview with Highsnobiety that she “has a hard time falling in love.”

“It’s a scary thing, dear. It’s really scary,” the actor admitted.

Festive: The bash was themed holiday

Festive: The bash was themed holiday

Eilish also addressed the scrutiny their relationship has experienced due to their 11-year age difference.

“Say what you have to say, but right now I’m in control. I did that,” she told the publication.

“I’ve managed to push myself to a point in my life where I’ve not only been known by a person I thought was the hottest fucking f**ker alive, I’ve had his ass ripped off as well! Are you kidding me? Can we just [get a] Applause for me?’ she was amazed.

Arrive in style: Eilish arrived in a sled, drink in hand

Arrive in style: Eilish arrived in a sled, drink in hand

Just getting started: The night seemed to just keep getting better for Eilish and her guests

Just getting started: The night seemed to just keep getting better for Eilish and her guests

She continued, “I pulled his ass! All me! I did this! I locked up that motherf**ker!’

Eilish also addressed the scrutiny of their relationship.

“Say what you have to say, but right now I’m in control. I did that,” she told the publication.

Happy Birthday Billie!  Jenner, 27, and Hailey Bieber, 26, appeared to be having a blast at the event as they playfully posed with middle fingers in a photo booth

Happy Birthday Billie! Jenner, 27, and Hailey Bieber, 26, appeared to be having a blast at the event as they playfully posed with middle fingers in a photo booth

Not just a third wheel: Kendall and Bieber's close friend Jesse Jo Stark, 31, joined them in the photo booth

Not just a third wheel: Kendall and Bieber’s close friend Jesse Jo Stark, 31, joined them in the photo booth

Photobooth Fun: The three friends walked through the typical series of classic photobooth looks, flashing cheesy flashes, sticking out their tongues, kissing their lips and turning off the camera

Photobooth Fun: The three friends walked through the typical series of classic photobooth looks, flashing cheesy flashes, sticking out their tongues, kissing their lips and turning off the camera

Cute!  Hailey shared a snap of her husband Justin kissing

Cute! Hailey shared a snap of her husband Justin kissing

Eilish also revealed that her love language was physical touch as she described the qualities she needed in a relationship.

“I just have to touch skin all the time. Touching, cuddling and hugging, everything related to skin is really a big thing for me. And otherwise just freedom. You know, I don’t want to be controlled. I want to be trustworthy and I want space and I want love and attention and equal admiration is really important.”

The musician also said she was “extremely grateful” for her past relationship with Vorce.

New romance: Billie and Jesse made their red carpet debut at the star-studded 2022 LACMA Art+Film Gala last month

New romance: Billie and Jesse made their red carpet debut at the star-studded 2022 LACMA Art+Film Gala last month

“I’m very grateful for the relationship I was in last year and I think he’s so much happier now which makes me really happy,” she said.

Billie and Jesse made their red carpet debut at the star-studded 2022 LACMA Art+Film Gala earlier this month.

Though the pair were in high spirits, they were recently slammed online for their “disturbing” baby and old man Halloween costumes.

Sparked controversy: Although the pair were in high spirits, they were recently slammed online for their

Sparked controversy: Although the pair were in high spirits, they were recently slammed online for their “disturbing” baby and old man Halloween costumes