"And then this just happened guys!! IT'S A BABY BOY!! Everyone in the Oliver family is very surprised and beyond happy. He arrived safely," the proud father wrote on Instagram last evening.
"mum / @joolsoliver was really really amazing, unbelievably composed, natural birth and my two eldest girls got to come in at the very end as the baby was born which was amazing to witness."
Their newest family member, who doesn't have a name just yet, weighed in at 8 lbs.
"We're all hitting the hay. It's been a long day. Big love... Bless a little baby boy Woop Woop !!!!" he continued. "And love to all you mums out there how amazing you are. It blows my mind."
"Little baby boy Oliver has arrived. We are so very happy, blessed, grateful and totally in love all over again and so very proud of our two eldest daughters who cut the cord," she gushed online. "Jamie was my hero.