The four-year-old prince, who makes us go aww with his mischievous expressions, was standing alongside Princess Charlotte and cousin Savannah Phillips, who were busy enjoying the show.
Between games, they goofed off with their mother Kate Middleton as Charlotte attempted a headstand or two and the siblings chased each other around barefoot on the grass.
Among them was Adrina Price, who said: 'Sad to see George playing with a gun when the whole country has a gun/knife crime situation.
Prince George of Cambridge, Catherine, Duchess of Cambridge and Princess Charlotte of Cambridge attend the Maserati Royal Charity Polo Trophy at the Beaufort Polo Club on June 10, 2018 in Gloucester, England.
Newborn Prince Louis was not brought to the match, allowing Kate to spend more time with her older children. He and Kate also spent time playing with a rainbow slinky.
The young royal wore the Jersey polo shirt and shorts set, the Prince has previously been seen in a green version of the top but wore navy for the occasion.
However, it looks as though the third-in-line to the throne also suffered a little tearful moment on the day.
Harry had placed his hand on little Beatrice's mouth to stop her from talking, while late Princess Diana watched him from behind-just like Prince William watched Savannah and George-making us really nostalgic.
"For the royal family, that big appearance on the Buckingham balcony during the Trooping the Colour is a huge deal", said ABC News royal contributor Imogen Lloyd Webber.
"The Royals have either served in the armed forces or are married to someone who has served", royal expert Kelly Lynch, managing editor of Dailybreak, tells Yahoo Lifestyle.