William and Kate thanked well-wishers for messages of support they have received marking their eldest child’s milestone on Friday.
Four images have been issued by the royal couple showing the young prince in the grounds of their Norfolk home Anmer Hall.
A Kensington Palace spokesman said: “The Duke and Duchess hope that people will enjoy seeing these new photographs.
“They would like to thank everyone for all the lovely messages they have received as Prince George celebrates his third birthday.”
The first of the pictures, taken in mid-July by photographer Matt Porteous, show George standing barefoot on a swing. In another image he is sitting on the swing looking at the camera.
In the third, the prince is shown walking and in the final image he is sitting on a rug with the family pet Lupo.
Mr Porteous said: “I really enjoyed the opportunity to take these photographs of Prince George. It was a very relaxed and enjoyable atmosphere. I’m honoured that they have decided to share these images with the public to mark his third birthday.”
George is shown in three of the pictures wearing a striped blue T-shirt and dark blue shorts - which are likely to sell out when identified by royal watchers on social media.
In the fourth picture, where he has been captured walking, the young prince is wearing a striped jumper with the image of a whale on the front, beige shorts and dark trainer-style footwear.
The swing George is playing on is clearly carved with the names of his parents “William & Catherine”.
In the picture showing the prince with the pet dog, he can be seen holding a partially eaten ice cream lolly close to Lupo’s mouth.
The cocker spaniel is a strain of the breed traditionally bred for work as a gundog - and they can cause havoc around the house.