The royal arrived for his first day of school looking a little apprehensive as he walked through the gates of Thomas's Battersea just before nine o'clock, accompanied by his proud dad Prince William.
Kate was unable to accompany her first born because she is suffering with severe morning sickness.
George looked adorable in his new school uniform; navy shorts, a blue V-neck jumper emblazoned with the school's emblem, a light blue polo shirt, blue socks and black shoes.
He arrived holding hands with his dad, who was carrying his red and blue school rucksack. Father and son were greeted at the gates by the Head of Lower School Helen Haslem, and George politely shook hands with her before she walked the pair inside.
George turned four on 22 July and an official picture was released to mark his birthday. The prince, dressed in a stripy blue and white shirt, beamed out of the portrait taken at Kensington Palace.
The royal household said the Duke and Duchess of Cambridge were "very pleased to share this lovely picture". Chris Jackson, Getty Images royal photographer who took the portrait, said: "He is such a happy little boy and certainly injects some fun into a photoshoot."
George needed a little encouragement to exit the plane when he joined his parents and little sister Princess Charlotte for a red carpet arrival in Warsaw, Poland, as they went on a royal tour in the run-up to his birthday.
On the tarmac, shy George fidgeted, swung his right leg backwards and forwards before wrapping it around his left, and kept one of his hands inside the pocket of his trademark shorts.
Trudeau's high five
The Cambridges headed to Canada in September 2016 and George showed himself to be adept at demonstrating old-fashioned British reserve.
When popular Canadian PM Justin Trudeau attempted to greet him with a high five, low five and a handshake, the third in line to throne rebuffed the attempt with a shake of his head.
Helicopters in Hamburg
The Prince was thrilled when he got to clamber into the cockpit of two helicopters while in Germany.
George tried on a helmet, while Charlotte pushed buttons inside the aircraft. The Princess appeared to have a little tantrum outside - jiggling her legs before falling to the floor. She was quickly picked up by the Duchess of Cambridge.
The Prince could not contain his joy when he was taken inside the helicopters, at one point looking around wide-eyed and clasping his hands to his face in amazement.
On the balcony
The Prince stole the show when the royals celebrated the Queen's official 91st birthday at Trooping the Colour in June.
Resting his chin on his hand with a bored look on his face, George appeared unimpressed with the sight before him on what was his third appearance on the balcony of Buckingham Palace. But he cheered up a bit when he spotted the flypast.
George as pageboy
George - in gold knickerbockers - had a leading role at aunt Pippa Middleton's wedding in May.
The Prince was kept in check by his mother, who told him off after he appeared to step on the bride's carefully-arranged train.
Bubbles and balloons
George was transfixed by the bubbles and balloons at the children's tea party in Victoria, Canada.
The youngster enjoyed a ride on a miniature pony, ran around squirting his father and sister with an orange bubble gun and was shown how to blow bubbles by William.