The Duke and Duchess of Cambridge have named their daughter Charlotte Elizabeth Diana, Kensington Palace has said.
The fourth in line to the throne will be known as Her Royal Highness Princess Charlotte of Cambridge.
She was born on Saturday in the Lindo Wing of London's St Mary's Hospital weighing 8lbs 3oz (3.7kg).
The Queen and other senior royals were told of the baby's name before the announcement was made public.
Charlotte, the feminine form of Charles, has a long royal pedigree and became popular in the 18th century when it was the name of George III's queen.
The King bought Buckingham House in 1761 for his wife Queen Charlotte to use as a family home close to St James's Palace – it became known as the Queen's House and is now Buckingham Palace.
Charles is the name of two former Kings and of the Prince of Wales, the princess's grandfather.
Charlotte also has more recent connections for the royal couple. On the duchess's side, it is the middle name of her sister Pippa Middleton and on the duke's it is the name of his cousin Charlotte Spencer, Earl Spencer's youngest daughter.
The earl tweeted: "Perfect names. My 2-year old Charlotte Diana will be thrilled at cousinly name-sharing."
According to figures from the Office for National Statistics, Charlotte is the 21st most popular girl's name in England and Wales with 2,242 babies being given it in 2013.
Elizabeth is 39th in the list but Diana is not in the top 100.
The duke and duchess and their daughter have been at home in Kensington Palace since leaving hospital on Saturday evening.
It is understood they will remain there before travelling to their country home, Anmer Hall, on the Queen's Sandringham estate in Norfolk.
Earlier in the day gun salutes took place in London to mark the birth.
Volleys were fired by soldiers in Hyde Park and the Tower of London to honour the arrival of the new princess.