The royal welcomed her first child on Friday at Gloucestershire Royal Hospital in Gloucester.
The baby, whose name has yet to be announced, weighed in at 7lb 12oz. Proud father, rugby player Mike Tindall, was present for the birth.
A statement from the royal family added: "The baby's name will be confirmed in due course."
The little girl's great-grandparents, the Queen and Prince Philip, are "delighted" by the news, according to the statement.
The baby is 16th in line to the throne.