The photo was posted to nearly 10 million followers of their combined The Duke and Duchess of Sussex Instagram account on Thursday morning UK time.
It shows Prince Harry holding Archie during his Christening in July as his grandfather looks on. “Happy birthday to His Royal Highness The Prince of Wales — Sir, Pa, Grandpa!” the caption said.
Prince Charles has turned 71 and is currently the longest-serving heir apparent in British history.
The controversial couple have been fiercely protective of their newborn, with Archie only being seen publicly a handful of times in recent months, including on their recent trip to South Africa.
The Duke and Duchess of Cambridge and the Queen and Prince Philip also posted their own tributes to Prince Charles.
— The Royal Family (@RoyalFamily) November 14, 2019
— Kensington Palace (@KensingtonRoyal) November 14, 2019
The release of the picture came after it was revealed the Sussexes would not spend this Christmas — Archie’s first — with The Queen, breaking with long-held tradition.
It was thought they would spend thanksgiving in the US with Meghan’s mum Doria Ragland, 63, and return for Christmas at Sandringham.
But they informed Her Majesty, 93, they will not be joining her and Prince Philip, 98.
Harry has always spent Christmas at the Queen’s Norfolk home, except for 2012 when he was in Afghanistan — and for the past two years he has been joined by Meghan, 38.
“They need some time away to recharge and decide their plans for next year,” a royal source told The Sun.
Royal biographer Ingrid Seward said Her Majesty “might be a little hurt but she’s far too gracious to ever let it show or be known”.