Prince William's wife Kate gave birth on Monday (July 22) to a baby boy, who becomes third in line to the British throne, his office said.
The baby, the couple's first child, was born at 4:24 p.m. (1524 GMT), weighing 8 lbs and 6 oz.
"Her Royal Highness and her child are both doing well and will remain in hospital overnight," said a statement from the royal household.
The news has been displayed on an ornate easel in the forecourt of Buckingham Palace in line with tradition.
Prime Minister David Cameron said on Twitter: "I'm delighted for the Duke and Duchess now their son has been born. The whole country will celebrate. They'll make wonderful parents."
Presented by Adam Justice