Harry, 29, is a member of one of three teams involving injured soldiers that set out two weeks ago on the 200-mile (320-kilometer) Walking with the Wounded South Pole Challenge.
The charity said Friday that the teams arrived at the South Pole at 13:25 GMT (8:25 a.m. EST).
The challenge was initially a race but organizers suspended the competitive element last week due to harsh conditions.
Actors Dominic West and Alexander Skarsgard also were on the trek with teams from Britain, the Commonwealth and the U.S.
Harry, an army Apache helicopter pilot who has served in Afghanistan, spent several days in 2011 trekking with wounded servicemen on a similar expedition to the North Pole.