The seventh in line to the throne baby boy - an eighth great-grandchild for the Queen and the Duke of Edinburgh - arrived at 5.26am, weighing 7lb 3oz. "But this little thing is absolutely to die for, so I'm just over the moon", he said with emotions. "It's a new addition to the family and now would be a flawless opportunity for the family to get back together".
Armed British police officers stand on duty outside Windsor Castle on Tuesday.
A thrilled Harry, speaking on camera at Windsor Castle's Royal Mews, revealed that Meghan had given birth early yesterday morning and it was the "most unbelievable experience I could ever have possibly imagined".
The American a year ago made waves in Britain by closing her own vehicle door - a task usually performed by aides.
The new father, 34, revealed that the royal couple are "still thinking about names" after their son was born "a little bit overdue".
The luxury private hospital where Meghan is believed to have given birth offers new parents a "celebration meal" complete with champagne, lobster and foie gras.
The Buckingham Palace said the baby weighed about 3.2 kg and the royal family have been informed.
Home birth had reportedly been on the Duchess's mind.
A statement from Buckingham Palace made no mention of where the birth had taken place but went out of its way to note that Meghan's American mother, Doria Ragland, was at Frogmore Cottage to help support her daughter.
He said: "I'm very excited to announce that Meghan and myself had a baby boy earlier this morning, a very healthy boy". Likewise, many royal fans gathered in Windsor following the birth, where, a source told ET, Harry and Meghan welcomed their child at home at Frogmore Cottage.
The royal arrival has also been marked in different ways, including Niagara Falls being illuminated in blue and trees being planted in New Zealand.
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It is also possible Harry and Meghan will break tradition and give the baby a name without a long connection to the royal family.
An armed police officer stands guard as the Royal Regiment of Scotland band march by in Windsor on Tuesday.
With Meghan's focus on empowering women and Harry's devotion to raising awareness of mental health issues, the duke and duchess are already being billed as progressive parents.
A young child adjusts his hood as people wait for the Royal Regiment of Scotland band in Windsor on Tuesday.
The distance from the throne means the boy will nearly certainly never be sovereign, and will not have to adhere as rigidly to royal rules as cousins George, Charlotte and Louis will. "For us, I think we will be seeing you guys in probably two days time as planned as a family to be able to share it with you guys and so everyone can see the baby", Prince Harry confirmed with a big, first-time dad smile.
The duke even apologised about the short notice for the press conference and joked with a cameraman who said sorry for not wearing a tie, telling him "you're a cameraman, you can get away with it".
In Canada, Niagara Falls was bathed in blue light to mark the baby boy's arrival, while in Toronto the CN Tower was illuminated in purple.
Meghan gave birth at 5.26am on Monday May 6 United Kingdom time.
Meghan's estranged father Thomas did not attend either, creating a scandal that lingers on to this day.
"The baby is 7th in line for the throne, which is insane, because right now I'm 7th in line for the key-making kiosk at my grocery store", DeGeneres wrote.
Patrick J. Adams and Meghan Markle.