John Stamos and Caitlin welcome first baby boy

John Stamos, 54, welcomes first baby and reveals traditional name

The actor shared a gorgeous black and white picture of him and baby Billy

Andrea Caamano

John Stamos is no longer just an uncle, having welcomed his first baby with wife Caitlin over the weekend. 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.

"From now on, the best part of me will always be my wife and my son. Welcome Billy Stamos (named after my father) #NotJustanUncleAnymore #Overjoyed," he captioned the sweet black and white snap.

John Stamos shares first picture of baby Billy

Proud dad John with baby Billy

The actor was quick to receive messages of congratulations from both his fans and his Full House co-stars. Candace Cameron Bure, known for her role as D.J. Tanner on the hit show, commented on the snap: "Yes yes yes!!! I'm overjoyed for you and Caitlin. You guys deserve nothing but the best. I can't wait to meet Billy! Can I come over tomorrow."

RELATED: John Stamos announces engagement to Caitlin McHugh – see where he proposed

John, 54, first revealed he and wife Caitlin, 32, were expecting their first baby back in December, just two months after their fairy tale engagement at Disneyland. John told People at the time: "The [pregnancy] happened. Then I said, I better have a ring on her finger because it’s the right thing to do, and I wanted to marry her anyway. So I called her parents to ask, and it was like, 'You better!'"

John Stamos kissing Caitlins baby bump

John and Caitlin have been together for more than two years

"The look on John's face when I told him we were pregnant was priceless," added Caitlin. "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. Now it is!"

MORE: John Stamos admits he tried to get Olsen twins fired from Full House

John was previously married to actress and model Rebecca Romijn. The pair met when Rebecca modelled at a Victoria's Secret fashion show in 1994. John popped the question on Christmas Eve 1997 and they married the following year at the Beverly Hills Hotel in Los Angeles. Six years later, the couple announced their intention to divorce, which was finalised in March 2005.

More on: