The Prince and Princess of Wales have released a photo and a video to mark the milestone birthday of their eldest child, Prince George.

George, who turned 13 on Wednesday, is pictured at Kensington Palace in a portrait captured after he returned from Trooping the Colour on June.

The image was shared on Prince William and Kate’s social media, alongside the message “Happy 13th Birthday, George!” followed by a party popper emoji.

It was taken by Matt Porteous, the Waleses’ go-to photographer for family celebrations.

The formal shot was followed a few hours later by a new 18-second video starring George – repeating a pattern Kate and William started with the birthdays of their other children earlier this year.

It shows a smiling George waving at the camera. He’s also seen chatting on a boat ride, patting the family dogs, then playing cricket in the sand.

The video closes with George leading younger brother Prince Louis up a rocky hill overlooking the sea and fearlessly hopping over gaps in the rocks before taking a seat on one and pointing into the distance.

“Thank you for all the birthday wishes for George today!” the royal couple’s social media post was captioned.

Future king George is just weeks away from beginning at a new school. In September, he will follow in his father’s footsteps by attending prestigious Eton College, close to his Windsor home.

The newly minted teen was last seen out with his family when he and 11-year-old sister Princess Charlotte joined William and Kate in the royal box at Wimbledon.

Prince George with this mother Kate and sister Charlotte at Wimbledon two weeks ago. Photo: AAP

British wildcard Arthur Fery invited the siblings to play tennis with him when they chatted while attending the men’s singles final.

George, Charlotte and their younger brother Prince Louis are enjoying their summer holidays.

George has finished at Lambrook School, the private co-ed prep school in Berkshire where he occasionally boarded and his siblings also go. He is ready for his transition to boys-only Eton, where fees are more than £65,000 ($124,000) a year.

Prince George Alexander Louis was born in the private Lindo Wing of St Mary’s Hospital, Paddington, London, on July 22, 2013.

—AAP