Kate Middleton has given birth to a healthy baby boy on July 22, 2013.
The baby boy arrived at 4:24 PM BST, weighing 8 lbs 16 oz. The name of the royal baby has not been released but an announcement is expected when the family leaves the hospital. Royal watches predict that his name could be George or James.
Prince William released a brief message, saying, "We could not be happier."
The palace released a statement saying that the Duchess and the baby are "doing well" and will stay in the hospital overnight.
Clarence House tweeted: "The Queen and Prince Philip are delighted at the news of the birth of The Duke and Duchess of Cambridge's baby."
A link for a virtual card to sign to congratulate the new parents has also been posted by Clarence House.
Prince Charles of Wales also said in a statement: "Both my wife and I are overjoyed at the arrival of my first grandchild. It is an incredibly special moment for William and Catherine and we are so thrilled for them on the birth of their baby boy.
"Grandparenthood is a unique moment in anyone's life, as countless kind people have told me in recent months, so I am enormously proud and happy to be a grandfather for the first time and we are eagerly looking forward to seeing the baby in the near future."
The news of the baby's arrival was first given to the Queen. A bulletin, signed by the Queen's gynaecologist Marcus Setchell, whose team led the delivery of the baby, was taken to Buckingham palace under police escort.
"The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, Prince Harry and members of both families have been informed and are delighted with the news," the bulletin said.
Prime Minister David Cameron tweeted: "I'm delighted for the Duke and Duchess now their son has been born. The whole country will celebrate. They'll make wonderful parents."
The breaking news comes 10 hours after the Duchess of Cambridge checked into St. Mary's hospital with Prince William.
The pair arrived at the by car from Kensington Palace to the Lindo Wing at St. Mary's Hospital at 5:30 a.m. this morning.
The royal baby will become third in line to the throne, replacing Prince Harry. The baby will be given the title Prince and will become the future King of Britain.
"Historically, this is huge," CNN's royal expert, Victoria Arbiter, told Yahoo! Shine. "In 60 or 70 years, this baby will be a monarch. It's also the first time since Queen Victoria that four generations of monarchs will be alive together."
Royal fans have packed Buckingham Palace hoping to catch a glimpse of this moment in history and a full moon is lighting up the sky gloriously in England tonight.
