"Happy birthday to His Royal Highness The Prince of Wales - Sir, Pa, Grandpa!" read the caption.
The photo was posted shortly after Prince William and Kate Middleton took to Instagram to wish Charles a happy birthday.
The Duke and Duchess of Cambridge shared a series of sweet photos, including one of the royal with his grandson, Prince Louis.
"Wishing a very happy Birthday to The Prince of Wales!," they captioned the photos.
The royal is currently undertaking a two-day visit to New Delhi to strengthen the ties between India and the UK.
As part of his itinerary, Charles plans to cast a light on pertinent issues relating to climate change and the impact it is having on the nation.
RELATED: Kate Middleton laughs as she stumbles with Prince William
