Members of the 'Walking With The Wounded' expedition stood at the very bottom of the world at 12:00 GMT after more than three weeks of pulling sleds in Antarctica.
Twelve injured servicemen and women, some of them having lost limbs in the wars in Afghanistan and Iraq, took part in the 320-km walk.
The group endured temperatures as low as minus 35 degrees Celsius and wind speeds of 80 km an hour.
"The wind has dropped down, which is nice. I think everyone is feeling a bit tired but slowly getting into the rhythm. Only just got into the rhythm now and it has almost finished," he added.
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"We always knew that this wasn't going to be easy, but that is what makes the challenge so exciting. Our aim was to show that, despite injury, young men and women from our armed forces can still achieve great things," said Ed Parker, the expedition's director and co-founder of the Walking With The Wounded charity.
Team UK, which includes the prince and four injured British soldiers, were accompanied by a US team and another made up of Canadians and Australians.
Harry, who is patron of the expedition, also took part in the charity's trek to the North Pole in 2011 but withdrew early to attend his brother William's wedding to Kate Middleton.
Though Queen Elizabeth II's grandson is the first royal to reach the South Pole, Britain's monarchy has a number of links to the icy landmass.
Harry's aunt Princess Anne has twice visited Antarctica, most recently in 2007.
The Queen herself had a major chunk of Antarctica named after her in a gift from the British government to mark her diamond jubilee in 2012.