The 23-year-old served in Afghanistan with other members of his Household Cavalry Regiment last winter but was flown home in February after just 10 weeks when a media blackout collapsed, sparking fears that worldwide coverage of his deployment would make him a prime target for pro-Taliban insurgents.
Harry took part in a march with around 160 soldiers from his regiment through the streets of Windsor, where Harry's regiment has its headquarters.
The troops were then presented with the Operational Service Medal (OSM) for Afghanistan by Princess Anne.
Harry secretly flew to the southern Afghan province of Helmand in mid-December 2007 to work as a forward air controller, calling in air strikes to let pilots know where their targets were.
He was the first member of the royal family to see active service in a theatre of war since Prince Andrew flew helicopters during the Falklands war 26 years ago.
Prince Charles, Prince William and his girlfriend Chelsy Davy attended the service where he was awarded the medal.
William, 25, paid a brief and secret visit to Afghanistan last week to meet frontline British troops. The prince, who recently won his RAF wings, flew a military transport plane for part of the journey to Kandahar and spent three hours at the airfield.
British forces have been fighting in Afghanistan for six years, but are struggling to hold out against a resurgent Taliban force which, according to U.S. intelligence assessments, now controls at least 10 percent of the country.
Around 7,800 British troops are currently serving there, mainly in the south. A total of 95 British soldiers have died during operations.
Last week, the regiment suffered its latest loss when Trooper Ratu Babakobau was killed after his vehicle drove over a mine in Helmand Province.
