Her name is anyone's guess for now, but Kensington Palace has released details of the birth, ahead of posting a formal notice on the front of Buckingham Palace, as is tradition. The official release is entitled, "The Duchess of Cambridge Has Been Delivered of a Daughter."
With William on hand, the baby was "safely delivered" at 8:34 a.m. She weighed in at a healthy 8 lbs., 3 oz.
She is fourth in line of succession, after Prince Charles, her father, and her brother. She will be known as Her Royal Highness Princess (something adorable, we hope!) of Cambridge.
The Queen and Prince Philip, Prince Charles and Camilla and Prince Harry have expressed that they are "delighted with the news."
Now that the biggest baby event of the year has happened, we can start the baby-name watch!