"The Duke and Duchess of Cambridge are delighted to announce that they have named their son Louis Arthur Charles," Kensington Palace announced in a statement tonight.
"The baby will be known as His Royal Highness Prince Louis of Cambridge."
The Duke and Duchess welcomed little Louis on April 23 at 11:01, with Kensington Palace announcing the news via Twitter.
Speculation was rife over what name the royal couple would choose, with Arthur, Albert, James, Philip, Thomas, Edward and Fred as standouts, however, Louis wasn't among the top picks.
As is royal tradition, the couple had to inform the Queen of their intended name before officially announcing it.
Wills and Kate introduced Prince Louis, who is now fifth in line to the British throne, on the steps of The Lindo Wing at St Mary's hospital as they did with both Prince George and Princess Charlotte.
Weighing in at 3.8kgs, the little prince has already broken a royal record, not only was he Kate's heaviest bub, but he's also the heaviest male royal in 100 years.