Parker Liautaud, a Geology and Geophysics student at Yale University, has also become the youngest man to have skied to the South Pole.
The teenage environmental campaigner and his expedition partner Doug Stoup set a new world record for the fastest journey from the coast of Antarctica to the South Pole.
Liautaud, who was born in California and brought up in the UK, has already been on three expeditions to the North Pole, the first when he was just 15.
"The whole journey is really a mental one, managing uncertainty and trying to figure out how to manage risk. It is really a big relief to know that we have done it," Liautaud said after reaching the South Pole on Christmas Eve.
Christian Eide, from Norway, held the previous coast-to-Pole speed record by making the trip in 24 days.
Liautaud said the most challenging part of the South Pole expedition was the "mental game" he had to play.
At the age of 15, Liautaud had attempted to be the youngest person to reach the North Pole, but his team had to evacuate just 24 km from the end of their trip.
A year later, he completed an expedition to the North Pole.
