The cosmetics mogul and her mother were on hand as Chalamet celebrated the upcoming release of his fantasy film in L.A. on Sunday

Timothée Chalamet, Kylie and Kris Jenner. PHOTO:

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Kylie Jenner is supporting boyfriend Timothée Chalamet during his big night in Los Angeles — alongside her mom, Kris Jenner!

The Kylie Cosmetics founder, 26, and her mother, 68, stepped out Sunday night to attend the premiere of the actor’s new movie Wonka at the Regency Village Theatre, a source tells PEOPLE.

According to the insider, Kylie and Kris slipped into the theater following the film’s opening credits.

Kylie and Chalamet, 27, first sparked romance rumors in April after DeuxMoi, a celebrity gossip account, received an anonymous tip that named Kylie as the actor’s “new girl.” A week later, TMZ photographed her Range Rover in Chalamet’s driveway.

Timothée Chalamet attends Los Angeles premiere of ‘Wonka.’. Kylie Jenner and Timothée Chalamet’s Relationship Timeline

Several months later, the two confirmed their status by sharing a steamy smooch in the middle of a Beyoncé’s Renaissance concert at Sofi Stadium in September. The outing marked their first public appearance — and the first time fans saw them together.

A source told PEOPLE on Monday that Kylie is “incredibly happy” with Chalamet and has even put a label on their romance, calling him “her boyfriend.”

As for the Dune: Part Two actor, the insider said he’s “in awe of everything” The Kardashians star “is accomplishing,” and “especially thinks she is an amazing mom.”

“He is very supportive of her career and she of his,” the source continued. “They both try to attend important events for each other.”

“He is very good for Kylie. Since dating him, she seems very content, relaxed and focused. Her family loves him,” they added of Chalamet.

Kylie Jenner and Timothée Chalamet.

TAYLOR HILL/FILMMAGIC ; STEPHANE CARDINALE – CORBIS/CORBIS/GETTY

Hugh Grant Jokes Costar Timothée Chalamet ‘Gave Me Good Gossip’ on the Wonka Set (Exclusive)

Chalamet stars as the titular candymaker in Wonka, a prequel to Roald Dahl’s 1964 children’s book Charlie and the Chocolate Factory that features singing and dancing among its cast, including Chalamet.

Speaking with PEOPLE recently about the family-friendly film, directed by Paul King, Chalamet said Wonka is now his mother Nicole Flender’s “favorite movie” he’s done yet.

“I think she saw Bones and All and said, ‘You gotta be happier in your movies!’ ” he added, joking about his R-rated 2022 cannibalism film.

“But,” Chalamet continued of Wonka, “this is the tradition. I come from a musical-theater family, and this is more in line of the kind of movie I would’ve thought I’d be doing 10 years ago, if I was lucky enough to work at all.”

“This was so fun to work on. This was unlike anything I’ve ever worked on, I think,” he said.

Wonka is in theaters Friday.