Pictures taken by Princess Catherine showed the smiling two-year-old outside her Kensington Palace home in London before she set off to begin at the nearby private Willcocks Nursery School.
The princess will be a full-time pupil at the nursery in London which charges £3,000 ($NZ5666) per term.
Charlotte is fourth-in-line to the throne behind her father, her elder brother George and grandfather Prince Charles.
Her parents are expecting a third baby in April.
Unlike previous senior royals, Prince William attended nursery school as a child and son George made the step up from nursery to primary school in September when he began at Thomas's Battersea, a private school in southwest London.
The Duchess of Cambridge, who is expecting her third child in April, was forced to miss her son's first day at school last year due to morning sickness.
The duchess is a keen photographer and when Princess Charlotte was born, she chose to take the official pictures herself.