The photos were taken by his mother, Kate Middleton, the Duchess of Cambridge.
It has become a tradition for the palace to release snapshots taken by his mother.
On Sunday, Kensington Palace tweeted a photograph of Prince George on a family holiday and wrote, “The Duke and Duchess of Cambridge are very pleased to share new photographs of Prince George to mark His Royal Highness’s sixth birthday.”
In a later tweet they added two more photos of George in an English soccer jersey with a big smile and wrote, “These two photographs were taken recently in the gardens at Kensington Palace by The Duchess of Cambridge. Thank you everyone for your lovely messages on Prince George’s Birthday!”
The prince turns six on Monday.
The Associated Press contributed to this report.