He made his first public appearance since his operation on Friday 11 May, attending the Royal Windsor Horse Show with his wife, the Queen.
The young royal inherited a love of horses from her grandmother the Queen, 91, and was taught to ride at a young age.
"One of the reasons that Prince Harry has wanted this wedding to happen quite quickly - this is really whirlwind by royal standards - is because his 96-year-old grandfather, the Duke of Edinburgh, is retired now and Prince Harry really wants him to be at his wedding", Nicholl said.
It sees competitors taking part in a range of events from show jumping to dressage, along with displays from The King's Troop Royal Horse Artillery and DAKS Pony Club.
He went to Windsor Castle to recover and hasn't been seen in public since.
His latest outing is perhaps the strongest indication yet that Prince Philip will in fact attend his grandson Prince Harry's wedding on 19th May.
That's the weather forecast Britain's Met Office has offered for Saturday in Windsor, England, where Prince Harry and American actress Meghan Markle are having their wedding.
Philip was photographed sitting at the wheel of a 4×4, chatting to the Queen through the vehicle's open window.
Shortly after the Duke of Edinburgh left the hospital, Buckingham Palace issued a statement saying "His Royal Highness would like to convey his appreciation for the messages of good wishes he has received".
Despite the pain from his operation, an insider reported he was doing laps of the palace and walking up and down stairs in a bid to get his fitness up.
Although he has officially stepped down from all royal duties, he was forced to miss several important events including the traditional Easter Sunday service and the Maundy service.