Bobby Cannavale and Rose Byrne Credit: Bruce Glikas/FilmMagic

Baby for Byrne! Rose Byrne and Bobby Cannavale have welcomed their first child together. 

The proud papa revealed on CBS' The Late Show with Stephen Colbert on Friday, February 5, that their son was born earlier this week.  

Cannavale said his "beautiful" baby, who they've named Rocco, arrived on Monday, February 1. "You know, I didn't do anything ... and I'm so tired," the Vinyl star, 45, told Stephen Colbert. "I think I've gained 28 pounds since Monday."

Colbert asked if the newborn was named after Saint Rocco.

"Actually, yeah, patron saint of the sick ... pretty sure," Cannavale said. "Could be wrong. I'm tired."

The host joked that it sounded like Rocco could be the patron saint of prizefighters. "Totally, totally," the new dad replied. "Or made guys. The patron saint of made guys."

The X-Men: Apocalypse actress, 36, debuted her growing baby bump at LAX airport back in October, but the couple were tight-lipped concerning details of her pregnancy. 

Byrne and the Boardwalk Empire alum began dating in 2012. Since then, they've worked together in 2014's Annie and Adult Beginners and 2015's Spy. Byrne opened up about their onscreen projects in June.

"Making a film is an intense experience," the Australian star told Who magazine at the time. "To experience it with your boyfriend is quite fun."

Byrne enjoys their one-on-one time, too. But that doesn't mean romance is her forte. "To be honest, I'm not naturally that much of a romantic person — Australians don't like making a fuss," she told Elle magazine two years ago. "I have trouble with things that feel very manufactured, like Valentine's Day. I'm trying to get better at romance."

She added, "I'm not a good cook, but seeing someone enjoy what you've made is so satisfying."

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