Seeing as his title is Prince George of Cambridge, the royal tot will be going by the name George Cambridge at school, according to the Guardian.
And this was confirmed by the name tag spotted on the four-year-old's bag as he was pictured walking into school at Thomas's Battersea on 7 September.
Elliot Wagland, head of pictures at London Evening Standard, tweeted a zoomed-in photo of the label on the bag that read: "George Cambridge".
The speculation over Prince George's surname came due to the fact most members of the royal family do not use a surname.
"Members of the Royal Family can be known both by the name of the Royal house, and by a surname, which are not always the same," the royal website reads. "And often they do not use a surname at all.
"For the most part, members of the Royal Family who are entitled to the style and dignity of HRH Prince or Princess do not need a surname, but if at any time any of them do need a surname (such as upon marriage), that surname is Mountbatten-Windsor."