Spectators said he looked strange when he climbed into his car for the two-hour return trip to Highgrove, Gloucestershire.
On Monday, the Duke of Cambridge said his grandfather was “OK”, saying: “They’re keeping an eye on him.”
The Royal Family has continued with official duties since his admission to hospital.
The morning after the Duke ‘s arrival, Prince Charles and The Duchess of Cornwall, who received the Covid injection, visited Queen Elizabeth Hospital in Birmingham to learn about vaccine testing.
Last Thursday, The Queen made her first official event of the year, making one of her senior officials as Commander-in-Chief of the Royal Victorian Order at a reception at Windsor Castle.
The Duke has been wearing the latest lock with the Queen at Windsor. They both received their Covid vaccines in January.
The Duke last had a spell in hospital in December 2019, when he was treated for a “pre-existing condition” before being released on Christmas Eve after four nights.