Proud father, England's Duke of Cambridge, said he was “very happy” following the birth his newborn baby daughter.
William smiled broadly and waved at the crowds before driving himself away from the Lindo Wing to be reunited with son Prince George at Kensington Palace in London.
He said: “I’m just going to pick up George.”
On his return, Prince George waved to crowds as he was brought to hospital to meet his new baby sister for the first time by the Duke of Cambridge.
William waved to the crowds and his son copied him, and as they posed for a few moments for the world’s media the Duke kissed his son’s head before going into the Lindo Wing at St Mary’s Hospital in Paddington, London.
The Duchess of Cambridge gave birth to the new princess just over seven hours ago.
The baby weighed 8lbs 3oz and her name has yet to be announced.
William and Kate’s second child was delivered at 8.34am today, less than three hours after the Duchess was admitted to the private maternity unit at St Mary’s Hospital in Paddington, London.
George has been cared for by his nanny, and William will presumably be the one to tell the youngster the news about his new sister.
To shouts from the media about his reaction to the new arrival, the Duke replied that he was “very happy, thank you,”
The announcement of the birth left the Prince of Wales – who said he wanted his second grandchild to be a girl – and Duchess of Cornwall “absolutely delighted”, Clarence House has said.
William’s uncle Earl Spencer also reacted with joy to the announcement, saying: “It’s wonderful news – we are all thrilled for all four of them.”
Other members of both families – the Windsors and the Middletons – have been informed including England's Queen and Duke of Edinburgh, and Prince Harry who is on the other side of the world in Australia.