The Duke and Duchess of Cambridge have released a photograph of Princess Charlotte and Prince George taken outside Kensington Palace before they left for St Thomas’s.
Other pictures taken by the press have also been released.
And as she arrived at the school, Princess Charlotte, four, was photographed by the press meeting head teacher Helen Haslem.
Her uniform includes a navy pleated skirt and cardigan, white socks and black shoes.
The duchess carried her daughter’s backpack, which was decorated with a pink key-ring in the shape of a pony’s head. She smiled as she greeted Ms Haslem and asked about her summer holidays.
Ms Haslem bent down to shake hands with both George and Charlotte, who is fourth in line to throne.
The duke and duchess accompanied Charlotte to her classroom before saying their goodbyes.
Prince William, who drove the family to the school, said: “First day – she’s very excited.”