The baby was born at 5:26 a.m. London time and weighed 7 pounds 3 ounces. Prince Harry said he was "incredibly proud" of his wife, and while their son was a little bit overdue, it had given the royal couple more time to contemplate names.
"I'm just over the moon," Prince Harry said.
The 34-year-old Harry, speaking before TV cameras on Monday afternoon in Windsor, said he was present for the birth.
"It's been the most amazing experience I could ever have possibly imagined," he said. "How any woman does what they do is beyond comprehension...We're both absolutely thrilled and so grateful for all the love and support from everybody out there. It's been amazing, so we just wanted to share this with everybody."
Harry said he was ecstatic about the birth of their first child and promised that more details - such as the baby's name - will be shared in the coming days. The couple said earlier they weren't going to find out the baby's sex in advance.
ABC News royal contributor Alastair Bruce said Tuesday on Good Morning America that while the child's title is not yet official, it is expected to be the "Earl of Dumbarton", which is the second title given to the Duke of Sussex on marriage.
"The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, The Duke and Duchess of Cambridge, Lady Jane Fellowes, Lady Sarah McCorquodale and Earl Spencer have been informed and are delighted with the news," the royal family said in a statement.
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Meghan's mother, Doria Ragland, was reportedly also with her daughter and said she is overjoyed, according to British media. Senior royals were informed of the birth, as was the family of Diana, Harry's late mother, before he went before the cameras.
"The Duchess's mother, Doria Ragland,...is with Their Royal Highnesses at Frogmore Cottage," the royal family said. "Her Royal Highness and the baby are both doing well."
The little bundle of joy is Queen Elizabeth II's eighth great-grandchild and is seventh in line to the throne behind grandfather and current heir Prince Charles, uncle Prince William, cousins Prince George, Princess Charlotte and Prince Louis, and dad Prince Harry.
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The arrival of their first child marks another milestone at the end of a big year for the couple. They were married on May 19, 2018, and since then have been on trips around the world and have had countless sweet moments interacting with the public.
America's favorite royal, who grew up in Los Angeles and attended Northwestern for college, reportedly met Prince Harry in the summer of 2016, just months before the couple went public.
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The couple recently moved to Frogmore Cottage on the grounds of Windsor Castle where they got married. The nursery there is reportedly eco-friendly and gender-neutral in design, according to AP.
(The Associated Press contributed to this report)
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