The 54-year-old, well known for playing Uncle Jesse on Full House, shared the exciting baby news on Instagram with this photo. "Welcome Billy Stamos (named after my father)", Stamos captioned a photo of the newborn.
John Stamos and Caitlin Stamos made headlines when they married shortly after announcing Caitlin is also pregnant with John's first child.
The pair's arrival comes after they tied the knot in Studio City, California in February.
Stamos announced he was going to be a father back in December. The Fuller House actor revealed the news to his over two million fans on Instagram on Monday, sharing a gorgeous shot of him doing skin to skin with his new bundle of joy.
"I always wanted to be a dad. I've been practicing for a long time", Stamos told PEOPLE, referring to his TV roles. "I'll probably just do all that stuff", he joked.
This is John's second marriage - he was previously Wednesday to actress Rebecca Romijn from 1998 to 2005. I know my parents are smiling down. "It was the look of a man who has wanted a family of his own but wasn't sure it was going to happen for him. People would say, 'You should have a child.' I was like, 'That ship has sailed, '" he admitted at the time.