The multi-instrumentalist's wife Brooke gave birth to Charles Robert Cook on Friday (04Nov16), and the country star announced the news on Instagram with a photo of mum and son.

He added the caption: "This is Charlie. In this picture are the 2 most important things to me in this world. He & Mommy are well... I'm so in love!"

The Zac Brown Band also shared the baby news on Twitter with a shot of bearded Clay gazing adoringly at his son.

He's not the only new dad in the band - Coy Bowles and his wife Kylie welcomed their first child, daughter Hattie, on 21 October (16).

His Chicken Fried bandmates announced the news on social media, and Coy confirmed the delivery, writing, "Mother and baby are happy and healthy. Life is good. And the journey begins."

He also posted a photo of himself, mother, and baby sleeping.

Kylie and Coy wed in 2013. They became engaged after he proposed onstage at a Zac Brown Band show at Madison Square Garden in New York.