She weighed 8lbs 3oz and Kensington Palace twitter feed has announced that both mum and baby are doing well.
The town crier announced news of the birth outside the doors of The Lindo Wing at St Mary's Hospital in London where some fans have been camping for weeks waiting for The new Royal to be born.
The new princess is 4th in line to the throne and as yet has no name.
We wish them every luck for the future and hope they find that their Maternity Nurse, that's been reportedly booked to help with the disrupted nights that follow, is a huge help to them and enables them to enjoy their baby a little less sleep deprived than they otherwise would be!
What are your predictions for the new royal's name to be?
Does your baby share a Royal Birthday with the Royal Baby? COngrats to all you other parents who have had babies born today too!