The Queen and the Royal Family have greeted crowds from the balcony of Buckingham palace and watched the RAF fly-past.
The Queen smiled as aircraft took to the skies to celebrate her 90th birthday.
Princess Charlotte joined her family - including older brother Prince George - on the famous frontage of the London landmark for the first time.
The Trooping of the Colour took place earlier on Horse Guards Parade as part of the second day of celebrations.
Queen will be guest of honour at a huge street party on Sunday as three days of celebrations to mark her 90th come to a spectacular close.
At 13 months old, Charlotte is almost the same age as the Queen was when she first appeared on Buckingham Palace's balcony 89 years ago.
The Queen's official birthday is set to be marked today by a Trooping the Colour parade held in her honour.