Isla is the daughter of Peter and Autumn Phillips and the granddaughter of Princess Anne. She has one sibling, her older sister Savannah, age 11 – there is just a year and three months between the girls and we often see them having fun together at sporting events with their parents.
WATCH: Royal family members as babies!
We wonder how the family are celebrating Isla's special birthday on Tuesday. One's first birthday in double figures is a big milestone! Here we look back at Isla's life so far…
Aw just look how cute Isla was as a baby! Mum Autumn carries her little girl at the Golden Metropolitan Polo Club Charity Cup polo match back in June 2012.
A very sweet toddler Isla running around with her older sister here at the Gatcombe Horse Trials at Gatcombe Park, Stroud, in September 2013.
Isla plays chase with her relative Lady Louise Windsor at the Royal Windsor Horse Show in May 2015. What a pretty dress!
Dad Peter gave Isla a lift on his shoulders when they attended the Gatcombe Horse Trials back in March 2016.
Isla and her cousin Mia, daughter of Zara Tindall, grab a bite to eat together at an equestrian event in March 2017.
It's a formal royal event for Isla at the 2018 Trooping the Colour parade in London. Here the young royal looks out from the balcony of Buckingham Palace.
Isla hangs out with her sister and cousin Prince George at the Maserati Royal Charity Polo Trophy at the Beaufort Polo Club in June 2018. We loved her cool jumpsuit.
The young royal made the sweetest flower girl at the wedding of Princess Eugenie and Jack Brooksbank in October 2018. Isla was joined by Princess Charlotte, her sister Savannah, Maud Windsor, Theodora Williams and Mia Tindall.
Isla gets a piggyback from her big sister at the 2019 Festival of British Eventing at Gatcombe Park. Looks like they had a fun time!