Kate and George were spotted driving into Buckingham Palace, where they spent part of the morning. It is thought that following the short visit, they headed back to Kensington Palace, where a party will be held later in the evening.
CLICK ON PHOTOS FOR GALLERY
The Duchess of Cambridge and Prince George in official birthday pictures
The Duke and Duchess of Cambridge will hold the afternoon tea party inside their apartment however Her Majesty's husband, the Duke of Edinburgh, is thought not to be attending due to other engagements.
Close family members, friends, and the Prince's godparents will all celebrate George's birthday with Kate and William, and the Queen is also expected to attend.
John Loughrey, was one of the early risers heading to the official residence to help decorate
George's grandparents Prince Charles and the Duchess of Cornwall are also thought to be skipping the party as they are in Scotland on annual leave.
Royal fans rose early to visit the palace gates on Tuesday. One fan, John Loughrey, was one of the well-wishers heading to the official residence of Prince William and Kate to decorate the famous gates with birthday balloons, banners and a Union Jack flag.