Billy Joel’s youngest daughters make a rare appearance at his MSG show — and perform!

They’re just a pair of Uptown Girls.

Billy Joel surprised his fans by performing with his youngest daughters, Della and Remy, on Tuesday night.

Joel brought Della, Rose, 8, and Remy Anne, 6, onstage to sing a rendition of the holiday classic “Jingle Bells” at Madison Square Garden in New York City.

The siblings rocked matching green leather dresses for the very rare appearance. After the show, the musician shared a photo of his little ones via Instagram.

“Some special guests at show,” the “Everybody Loves You Now” singer captioned the collage, which also featured fellow musician Elvis Costello.

Joel shares both children with his fourth wife, Alexis Roderick, whom he married during his Fourth of July party in 2015.

The “We Didn’t Start The Fire” hitmaker is also dad of singer Alexa Ray, 36, with ex-wife Christie Brinkley.

Joel was in good company on Tuesday night. In addition to his loved ones, “Barbie” director Greta Gerwig and her husband, Noah Baumbach, were spotted in the audience.

This is not the first time that Joel has performed live with his children.

In 2018, Della Rose helped her famous father belt out his 1980’s hit “Don’t Tell Me Why” at the iconic venue.

Clad in pink Christmas pajamas, the toddler did her best to sing what her father described to be be one of her favorite songs.

During the same concert, Ray also sang a rendition of “Have Yourself a Merry Little Christmas,” which was made famous by Judy Garland in the 1944 film “Meet Me in St. Louis.”

“We like to roll the family in [at Christmas],” Joel said in a video that was posted of the performance.

In June, Joel announced he will conclude his monthly residency at Madison Square Garden after 150 shows in July 2024. The record-breaking residency first kicked off in January 2014.

“It’s hard to believe we’ve been able to do this for 10 years,” Joel said at a news conference at the time. “I’m now 74. I’ll be 75 next year. It seems like a nice number.”

He added: “I’m kind of flabbergasted that it lasted as long as it did. My team tells me that we could continue to sell tickets but 10 years, 150 shows – all right already!”

Joel has been staying busy off stage, too. Last month, a new exhibit honoring the Grammy winner opened at the Long Island Music and Entertainment Hall of Fame.

“Billy Joel: My Life — A Piano Man’s Journey” explores his more than 50-year career.

“We were surprised because he had never ever OK’d an exhibition that involved his career or himself,” exhibit curator Kevin O’Callaghan told The Post. “He’s a very humble guy.”

According to the New York native, the idea of having something so vast being dedicated to him was “overwhelming.”

“It’s a little overwhelming,” Joel said prior to the exhibit opening. “Have you ever found yourself surrounded by you? It’s kind of a nightmare.”

Despite his reservations, Joel said the exhibit was a nice reminder of the life he’s led.

“I guess I’ve lived,” he said.

The exhibit is slated to stay at the LIMEHOF through the summer of 2024.