Prince George won hearts as he stole everyone's thunder at the Trooping the Colour ceremony.
The young royal joined the royal family on the balcony to watch the military parade to mark the official birthday of the Queen.
Earlier, he was caught on camera watching the parade from a window, with his nanny. The excited toddler laughed and smiled as members of his family joined the military procession.
The Prince of Wales, who is Colonel of the Welsh Guards, the Princess Royal, Colonel of the Blues and Royals, and William, Colonel of the Irish Guards, arrived there on horseback in full military regalia.
The Queen and Duke of Edinburgh travelled in an Ascot Landau vintage carriage from Buckingham Palace, along The Mall to Horse Guards Parade, where the Trooping the Colour parade was held.
Wearing a blue and white floral pattern dress by Catherine Walker, Kate was riding separately in an open-topped Barouche carriage alongside Camilla, Duchess of Cornwall, and Prince Harry.
Prince Harry was also pictured dressed in the uniform of the Household Cavalry, where he remains a Commissioned Officer, having quit active service at the end of last month.
The Duke of York rode with his daughters Princesses Beatrice and Eugenie, and the Duke of Kent and the Duke and Duchess of Gloucester travelled in the last carriage.
The procession was accompanied by a Sovereign's Escort of the Household Cavalry, comprised of Life Guards and Blues and Royals, in their silver and gold breastplates and plumed helmets.
The Colour paraded at this year's event was the flag of the 1st Battalion Welsh Guards.
While the Queen inspected 1,100 soldiers of the Household Division at Horse Guards Parade George managed to upstage everyone, even his mother the Duchess of Cambridge, who was making her first public appearance since leaving hospital after the birth of Princess Charlotte.
Dressed in a baby-blue outfit trimmed with white frills, his appearance was reminiscent of Prince William's first appearance on the balcony 31 years ago, when he was held by his father Prince Charles.
As the family stepped onto the balcony to watch the traditional RAF fly-past, Prince George looked on in wonder at the scene, as a sea of people converged on the palace to witness all the pomp and pageantry of the grand occasion.
Nine Red Arrows, one Sea King helicopter, two Chinook helicopters and one Puma 2 helicopter featured in the dramatic fly-past which was curtailed due to the weather.
But the grey skies did nothing to dampen the enthusiasm of the young royal. The one-year-old, who was held by his father the Duke of Cambridge, looked up in fascination as the aircraft roared past to conclude the ceremony.
George, the future King of England, who is third in line to the throne, waved to the crowd as he made his exit.
The Queen's actual birthday was 21 April, when she turned 89. Her official birthday is traditionally celebrated on the second Saturday of June when the weather is considered to be more predictable.