Kensington Palace released two photos of Charlotte to mark the occasion. Charlotte's mum Catherine took the pics.
The Duke and Duchess of Cambridge escorted their 2 1/2 year old daughter on her first day and helped her settle in to her morning class routine.
Willcocks has a strong emphasis on numeracy, early reading, poetry, art, crafts and music. The classes are structured but allow plenty of time for free play.
Charlotte's older brother George attended Westacre Montessori School in Norfolk as the family was based at Amner Hall at the time. George started "big school" at Thomas's Battersea last September.
Kensington Palace has released a 2017 highlights video:
For our final highlights video, let's take a look back at some of the key family moments this year. pic.twitter.com/gwVftwrcso— Kensington Palace (@KensingtonRoyal) December 31, 2017
