The most famous baby on the PLANET is called Charlotte Elizabeth Diana.
Kensington Palace tweeted the new name on Bank Holiday Monday (4 May).
A statement posted on their official Twitter account said: "The Duke and Duchess of Cambridge are delighted to announce that they have named their daughter Charlotte Elizabeth Diana.
"The baby will be known as Her Royal Highness Princess Charlotte of Cambridge."
The Duke and Duchess of Cambridge are delighted to announce that they have named their daughter Charlotte Elizabeth Diana.— Kensington Palace (@KensingtonRoyal) May 4, 2015
The Princess is believed to be named in honour of her grandfather, as Charlotte is the feminine version of the name Charles.
Her middle names are clear tributes to great-granny Elizabeth and William's late mum Diana, who died in a car crash in 1997 when William was just 15..
The day after the baby was born, the Duke and Duchess of Cambridge thanked fans for their support after the birth.
Kensington Palace tweeted: "The Duke and Duchess are hugely grateful for the messages of congratulations they have received from people all over the world.
"It means a great deal to them that so many people have celebrated the arrival of their new daughter."
At the same time, they tweeted: "Prince Harry has said about his new niece: 'She is absolutely beautiful. I can't wait to meet her.'"
The Princess of Cambridge, who is now fourth in line to the throne, was born on Saturday, weighing 8lb 3oz.
Kate and William returned home to Kensington Palace less than 12 hours later.
Baby Charlotte is believed to be meeting the Queen for the first time on this week.
Welcome baby Charlotte!
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