The photograph was taken at Kensington Palace at the end of June by Chris Jackson, Getty Images' royal photographer.
Kensington Palace shared in a statement: "The Duke and Duchess are very pleased to share this lovely picture as they celebrate Prince George's fourth birthday, and would like to thank everyone for all of the kind messages they have received."
George’s parents, Prince William and Princess Kate, both 35, revealed George's excitement about his upcoming birthday with well-wishers in Germany. William told a group of students in Hamburg, "George has got a big tummy. He'll probably end up eating all his cake himself."
The royal couple joked that George would also be on "sugar overload" in Heidelberg after trying their hands at candy-making and sharing they planned to bring the sweets back to their children.
George will celebrate his birthday on Saturday Willliam and Kate's country home, Anmer Hall, in Norfolk after returning back from the families' five-day royal tour of Germany and Poland.
George received an early birthday gift from his German hosts as the family boarded their plane home. He was also surprised with a special treat, climbing into the cockpit of two Airbus helicopters. The little prince got behind the controls and donned a helmet shortly before the family's departure for the U.K.
The public caught glimpses of a growing George as he held his parents’ hands as the family arrived in and departed from Poland and Germany. George, who loves planes, was seen at one point pulling the hand of his father to be able to board the plane faster.
In other photos, George and Charlotte were seen looking outside the plane’s windows.
George’s trip to Poland and Germany marked his third royal tour. He traveled with his parents and Charlotte to Canada last fall and accompanied his parents to Australia and New Zealand in 2014 as a toddler.
This year will be one of change for George, who will begin school in September at Thomas's Battersea School, a private school in Battersea, South London.
George attended preschool at a Montessori school near Anmer Hall. The family will now be based in London and George be a full-time student at Thomas's Battersea, a coeducational school not far from the family's Kensington Palace base.
Kensington Palace said in a statement coinciding with the announcement that William and Kate were looking forward to George's next milestone: "Their Royal Highnesses are delighted to have found a school where they are confident George will have a happy and successful start to his education."
Thomas's Battersea enrolls around 500 students from a variety of backgrounds whom George will one day lead when he is king.
Today’s photo from Kensington Palace is the latest of several images released on George and Charlotte’s birthdays, many of which were taken by the Duchess of Cambridge. Take a look back at the official photos released for George’s three previous birthdays.