Britain's Defense Ministry said the April 3 landing on the Middleton family farm was planned and authorized as part of the prince's Royal Air Force pilot training.
British media is calling the exercise wasteful at a time when the military is stretched by wars in Iraq and Afghanistan and warned it risked testing the public's patience with the monarchy.
"The aircraft landed in the field, after taking all necessary safety precautions, and was on the ground for 20 seconds," the ministry said. "No one got on or off the aircraft."
The farm is 16 miles northwest of Odiham Air Force Base, where the prince began his flight.
William received his air force wings, the traditional badge given to graduate pilots, on April 11 after four months in the air force learning to pilot helicopters and planes. His training was designed to make him a competent, but not operational, flier.
News of the landing on the Middletons' farm comes as the air force faces criticism for allowing William to fly a Chinook helicopter from London to the Isle of Wight to attend a bachelor party for his cousin Peter Phillips on the day the prince was awarded his wings. William's brother Prince Harry was also on board.
The ministry said both flights were part of the prince's training.
Britain's News of The World newspaper on Sunday accused William of using military equipment as a taxi service while military resources are stretched.
"William's jaunts risk testing the public's patience with the monarchy," the newspaper wrote in an editorial.
British fighter jet pilots normally spend up to four years in training.
The pilot's training was part of William's preparations to eventually become king, when he will become the ceremonial head of Britain's armed forces.
He is an army officer and is due to serve a tour overseas, most likely on board a navy warship.
Defense officials said previously that William could be deployed to areas such as the South Atlantic, the Persian Gulf, the Pacific Ocean or the West Indies.