The prince had been feeling unwell for a short period and he walked into hospital unaided, a royal source said.
Britain's Prince Philip, Duke of Edinburgh greets guests at a garden party at Buckingham Palace in London on June 1, 2017.
A palace source told the BBC that the duke travelled to the hospital by vehicle, where he was admitted as a precaution on his doctor's advice. "His Royal Highness would like to thank everyone who sent their good wishes", the palace rep stated.
The prince and the Queen, 94, have been maintaining social distancing rules at Windsor Castle, because their age puts them at risk from Covid.
In 2019, the Duke of Edinburgh was involved in a vehicle crash when he attempted to pull out of a driveway near the Sandringham Estate in Norfolk. Elizabeth became queen in 1952, following the death of her father, King George VI.