"The Duke and Duchess of Cambridge are delighted to announce that they have named their son Louis Arthur Charles," said the official Twitter account of Kensington Palace alongside photos of the British royals introducing Louis outside St. Mary's Hospital in London.
"The baby will be known as His Royal Highness Prince Louis of Cambridge," Kensington Palace continued about the baby's official title.
Middleton and William welcomed Prince Louis on Monday. The baby entered the world at 8 lbs. 7oz. The new prince is fifth in line to the throne.