Archie was delivered at 5:26 a.m. - thought to be at the exclusive, $26,000-a-night Portland Hospital - and weighed 7 pounds 3 ounces.
Following Wednesday's photo call, the couple introduced their son to the Queen and her husband, Prince Philip, the Duke of Edinburgh.
She said in a television interview that her new son "has the sweetest temperament".
However, it appears the Duke and Duchess of Sussex wanted something different for their first born child - and presumably any future children, too.
Of course, Archie very well may be the royal's nickname - but there's always a chance he heard the moniker tossed around as a potential baby name by his uncle Prince Harry.More news: Netanyahu says Gaza campaign is not over despite ceasefire deal
Archie, a name of Germanic origin with meanings that include "genuine", "bold" and "brave", is an increasingly popular baby name in Britain.
The announcement came the same day Meghan and baby Archie made their first public appearance since his birth with Prince Harry at Windsor Castle, saying she had "the two best guys in the world".
Meghan declared motherhood to be "magic".
"His looks are changing every single day", Prince Harry said.
They were the brand of choice for the Queen (she bought 20 of their soft wool blankets for a newborn Charles) and since then their designs have been wrapped around many a royal newborn, including Prince Harry himself and Prince William.
Instead, the Duke and Duchess of Sussex have chosen Mountbatten-Windsor, in keeping with family tradition-and including a nod to the Duke of Edinburgh. "We're just so thrilled to have our bundle of joy". The 93-year-old monarch also has eight grandchildren, and four children.
Queen Elizabeth II visited her grandson at the Sussex's home in Windsor Castle ahead of the grand reveal.