Kunis gave birth to the couple's baby boy on Wednesday, and the news leaked on Thursday.
Now, the second-time parents have released a statement on the proud dad's A Plus website, revealing they've named the tot Dimitri - a clear nod to Mila's Russian roots.
"Today, A Plus is happy to announce that Dimitri Portwood Kutcher was born at 1:21 a.m. on November 30, weighing 8 pounds and 15 ounces. Dimitri is the couple's second child, after having their daughter Wyatt in October of 2014."
Read more: Mila Kunis and Ashton Kutcher ‘expecting a baby boy’
Ashton let slip the sex of the pair's unborn baby during an appearance on the Today show in America.
When host Savannah Guthrie asked how his daughter was dealing with the thought of becoming a big sister, the actor said little Wyatt was still trying to understand mummy was pregnant.
"She points to Mila and she's like, 'Baby brother', when she points to the belly, and then she points to dad and she goes, 'Beer!'" he said. "So I think she gets there's something in the belly but I don't quite think that she knows that it's not going to be a plastic doll yet."
Read more: Mila has high hopes for Doctor Wyatt
Little Wyatt turned two on 1 October, 2016.
Ashton also recently told U.S. chat show host Conan O'Brien he wanted to call his son Hawkeye - the nickname of his beloved Iowa state college football team, but the actor revealed his wife had shot down the idea, explaining the name "didn't fly" with Mila.
"It didn't cross the Mila threshold," he laughed.
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