Scores of people congratulated the couple on the birth, including Labour leader Jeremy Corbyn, Hollywood actress Mia Farrow and TV presenter Paddy McGuiness.
Kate Middleton and Prince William proudly showed off their son on the steps of the exclusive Lindo Wing at St Mary’s Hospital, Paddington.
The Duchess appeared to pay a subtle tribute to Princess Diana in a Jenny Packham dress as she welcomed the little prince to the world just seven hours after giving birth.
See photos of the baby and his parents below:
Royals traditionally keep the public guessing before revealing their choice.
William and Kate will want to share the name with the Queen and the rest of their family before making it public.