The It's Always Sunny in Philadelphia star and his actress wife, Jill Latiano, welcomed baby boy Miles Robert on Monday (12Sep11).
Announcing the news during an appearance on late night U.S. talk show Conan on Thursday (15Sep11), Howerton admitted the couple had waited until after the tot's birth to find a suitable name.
He said, "My wife and I thought it would be a good idea to wait to see the baby first before we actually decided what his name would be… get a sense of the guy.
"Then we saw him and he looked like a tiny little baby alien grandpa creature and I was like, ‘I’m not getting any information from this - at all.'"
Howerton and Latiano wed in 2009.
The Horrible Bosses star and his partner, Jill Latiano, will welcome the child later this year (11).
Howerton announced the news on Twitter.com by posting a picture of the pair at the Cowboys & Aliens premiere in Los Angeles, alongside the words, "Check out my beautiful preggers (pregnant) wife, y'all."
The news comes just days after Howerton's It's Always Sunny in Philadelphia co-stars Charlie Day and Mary Elizabeth Ellis announced they will also be welcoming a child this year (11).