Will Arnett and Girlfriend Alessandra Brawn Welcome Son Alexander Denison

The new baby boy joins Will Arnett's sons Abel, 9½, and Archie, 11, with ex-wife Amy Poehler, plus Alessandra Brawn's son Nash

Alessandra Brawn and Will Arnett
Alessandra Brawn and Will Arnett. Photo: Rachel Murray/Getty Images

Will Arnett is a father of three.

The LEGO Masters host, 50, and his girlfriend Alessandra Brawn welcomed their first child together, son Alexander Denison Arnett, on Wednesday, May 27, in Los Angeles, his rep confirms to PEOPLE.

"'Denny' is home and everyone is doing well," the rep shares.

The new baby boy joins Arnett's sons Abel James, 9½, and Archibald "Archie" William Emerson, 11, with ex-wife Amy Poehler, plus Brawn's son Nash.

PEOPLE confirmed Brawn's pregnancy in February.

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Alessandra Brawn and Will Arnett
Alessandra Brawn and Will Arnett. Amy Sussman/Getty Images

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Arnett and Brawn, the former CEO of clothing brand Chapel, reportedly began dating last year and attended the 2019 Creative Arts Emmys together last September.

The Arrested Development star opened up in 2016 about how he explains his fame to his children.

"I just tell them because of the nature of our jobs people see that more than if I was an accountant," he said at a press conference in New York while promoting Teenage Mutant Ninja Turtles: Out of the Shadows.

"People are familiar with your work so they know who you are and they want to, I guess, participate in that or whatever," Arnett added.

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"Never has the idea of celebrity meant less because we live in a day and age where you're famous for no definitive skill set other than being on social media," he continued. "People are like, 'Oh, he's an Instagram star.' But for what? It used to be you had to do something … it's bizarre."

Arnett added, "Even though there are elements that are kind of weird, I always appreciate when people are fans and like the stuff. I'm a fan of a lot of other people myself."

"I appreciate when people compliment you and let you know. I don't make it in a vacuum so nobody watches it," he said.