Prince William and Kate Middleton announced the name of their newborn son Friday as Louis Arthur Charles, Kensington Palace said.

"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.

Prince Louis is William and Middleton's third child together following Prince George, 4, and Princess Charlotte, 2. The couple have been married since 2011.

Prince Williams brother, Prince Harry, recently asked William to be his best man at his upcoming wedding to Meghan Markle on May 19.

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By Wade Sheridan, UPI.com

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