The three-year-old appeared to be having the time of her life at the event, rolling around in the grass and running about with older brother George, in the way that all kids do.
Prince George played with his slinky during the match.
Princess Charlotte had her mother Kate in stitches as she attempted a headstand. Professional acrobating might not be in her cards to be honest, but the little royal can definitely rock a pair of sunglasses.
Both he and Harry will be competing in a number of games in the name of charity in the coming weeks and we can't wait to see more of the fam relaxing, smiling and way away from the rigid formality of the palace.
It was widely assumed that Kate was playing with and chasing her children Prince George and Princess Charlotte, but photos taken from a different angle show the real reason for the Duchess' dash.
Many took to Twitter to criticize Will and Kate for allowing their son to play with a toy gun.
George and his friends were spotted playing with some toy guns.
Another said, "Prince George sitting out in the sun playing with toy guns and water pistols like every other normal child in the world is not the problem, it's the freaks who actually think it's newsworthy enough to pass comment and who are dying to be offended by it who are the problem".
George was no doubt delighted to be reunited with his cousin Savannah, who on Saturday was pictured cheekily covering his mouth with her hand as they watched the Red Arrows flypast from the balcony of Buckingham Palace.
"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. Pink was their go-to color for the 2017 Trooping the Colour.