The actor and his wife, Caitlin McHugh, who tied the knot back in February, have welcomed their first child, a son named Billy.
Stamos, 54, shared the happy news on his Instagram account on Sunday night, posting a sweet photo of his newborn son lying on his chest.
"From now on, the best part of me will always be my wife and my son," the Full House star captioned the heartwarming pic, in which his son's tiny hand is holding on to his ring finger. "Welcome Billy Stamos (named after my father) #NotJustanUncleAnymore #Overjoyed."
Earlier this month, Stamos opened up to ET about why impending fatherhood was making him "so emotional."
“I've waited my whole life for this,” he gushed at the premiere of longtime pal Bob Saget’s new movie, Benjamin. “I'm already so emotional and so excited... I've been dreaming about our baby. I mean, I am really excited.”
John Stamos Reveals His Baby With Wife Caitlin Will Have a Disney-Themed Nursery! (Exclusive)
After a lengthy career, Stamos said he sees his new, expanding family as the next step.
“I don’t know what I would do if I wasn't having a baby right now,” he explained. "I've done everything anyone could ever... I've had the most beautiful blessed life on the planet, and the most honest real thing I could do, I haven't done.”
Part of the reason the TV star said he feels so confident about this next stage of his life is having found “the right girl,” in McHugh, 32.
“She's so beautiful pregnant. She's so magical,” he said of his new bride. “She is the most graceful person I've ever met in my life, and she's handling pregnancy like a champ. Every day I say, ‘You're doing so great, you're doing so great.’ Just every day I'm with her I just realize, first of all, how lucky I am, but what a special human she is. She's magical. She floats into a room. I've never heard her say a bad word about anybody.”
See more about the sweet couple, and their new bundle of joy, in the video below.