The Duke and Duchess of Cambridge have named their new baby daughter Charlotte Elizabeth Diana.
The names will be seen as a triple homage to her grandfather Prince Charles, great-grandmother Queen Elizabeth II, and late grandmother Diana.
The child was born on Saturday, a sister for one-year-old Prince George.
Kate gave birth within three hours of being admitted to hospital.
William was present for the birth at 7.34am GMT (5.34pm AEST) and the princess weighed eight pounds and three ounces (3.7 kilograms).
William then left the hospital and returned with George to meet his little sister.
About 10 hours after the birth, the beaming Duke and Duchess of Cambridge left hospital carrying their newborn princess in front of hundreds of cheering well-wishers and the massed ranks of photographers from the world’s media.
The sleeping baby was wrapped in a woollen shawl as a relaxed-looking Catherine, 33, cradled her in her arms in front of the private Lindo Wing of St Mary’s Hospital in central London.
William, 32, then drove his wife and daughter the short distance to Kensington Palace.
The royal couple are planning to spend the next few days at Kensington Palace.
They will then travel to Anmer Hall, their secluded 10-bedroom country mansion on Queen Elizabeth’s privately-owned Sandringham estate in Norfolk, eastern England.
Gun salutes were fired across London to mark the birth.
Britain had been on tenterhooks for more than 24 hours waiting for the announcement, which came two days after her birth.
Kensington Palace tweeted that she would be known as Her Royal Highness Princess Charlotte of Cambridge.
In 1982, Prince William’s name was announced a week after his birth.
Charlotte became the hot favourite for bookmakers on Sunday, overtaking long-time favourite Alice. Victoria, Olivia, Elizabeth and Diana were also popular choices.
The baby is the first princess born into the British royal family since Princess Eugenie, daughter of the queen’s second son Prince Andrew, 25 years ago.