The couple also share 4-year-old daughter, Frances Laiz

Ben McKenzie and Morena Baccarin have welcomed another bundle of joy!

The Gotham costars announced Tuesday that their second child together, Arthur, has made his grand entrance into the world.

Both posted the same photo on social media of their newborn son lying on his side with his hands covering his face.

"Welcome to the world, Arthur. Gotta say, your timing is impeccable. ❤️," McKenzie, 42, captioned the photo.

Baccarin, 41, wrote: "2021 is looking up. Welcome to the world Arthur. Trust us, you haven't missed much yet."

Baccarin announced that she and McKenzie were expecting in December, showing off her growing baby bump during her appearance on The Talk.

The big reveal came when Baccarin was asked about a photo she had previously posted on her Instagram of McKenzie wearing colorful nail polish and several pieces of costume jewelry.

"Look, times have changed. What we now call date night is being able to take a walk outside together," Baccarin — who shares 4-year-old daughter Frances Laiz with the actor — said. "Ben very cleverly found a way to get them involved by asking Frances to help him get ready for the date. I don't think he was expecting the blue nail polish and the bracelets and everything, but I think it looks good on him."

After co-host Carrie Ann Inaba remarked that Baccarin was "glowing," the actress stood up to reveal her baby bump, saying, "I think that date was pretty successful."

Arthur is Baccarin's third child and McKenzie's second. Baccarin is also mom to 7-year-old son Julius from her previous marriage to director Austin Chick.

In September, McKenzie shared the photo of her and McKenzie's "parent date night" she was asked about on The Talk.

"Parent date night = the 4 yr old makes you 'fancy' " he captioned on Instagram.

Baccarin also posted the same shot from her account, writing, "When your four year old gets you ready for a date night."

The couple married on June 2, 2017 — Baccarin's 38th birthday — in a private ceremony at the Brooklyn Botanical Gardens in Brooklyn, New York.

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In 2018, Baccarin told PEOPLE that McKenzie has been nothing but a great parent to both of her children.

"It's wonderful to watch him every day with our kids," she said. "I couldn't ask for a better partner."