The image, which shows the highly photogenic prince sporting a cheeky smile, was taken in the garden of Clarence House after the christening of his baby brother Prince Louis on July 9.
The portrait was released by Kensington Palace on late Saturday, ahead of the young royal's actual birthday on Sunday.
"There'll be a time and a place to bring George up and understand how he fits in, in the world", the future King said in a previous interview.More news: Top 5 - Custom Tour de France Bikes
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George behaved with aplomb at his first official meet-and-greet, when he stayed up past bedtime to shake hands with visiting President Barack Obama at Kensington Palace on April 22, 2016.
Who can forget George's adorable christening pictures accompanied by his doting parents, William and Kate.
The little prince was very interested in the tail rotor.
Prince George's first day at Thomas's school in Battersea, London was indeed a global event with many comparing it with Prince William's school day accompanied by Lady Diana.
A few months after his last birthday George started his first day at school with dad William, but was without mum Kate.