And it's a move that comes with a hefty price tag: The Sun reports that for the three children to attend Lambrook full-time, annual fees will be an estimated £53,508 (NZD $102,006).
But the school, which the Duke and Duchess are said to have visited many times before enrolling their children there, has impressive credentials including a strong focus on sports and an array of elective subjects from scuba diving and podcast making to bee keeping and tap dancing.
A roll of 620, the school scored "excellent" in its most recent UK Independent Schools Inspectorate and its head teacher, Jonathan Perry, writes on Lambrook's website: "We give our pupils the 'Feathers to Fly' so that when they move on to the next stage of their educational journey, they will spread their wings and take flight; leaving as confident, happy, engaging, mature, considerate and thoughtful young adults who are outward-looking global citizens."
Lambrook's proximity to the Cambridges' new home, four-bedroom Adelaide Cottage, is said to appeal to William who likes doing the school run and will be able to make most of the drive across private roads on Windsor Great Park to the school's gate.
According to The Sun, a Palace insider says the children are "very excited" about going to school together.
"This decision to move to Windsor and for George, Charlotte and Louis to go to school together was always about putting the children first. It is the best thing for the kids.
"Both William and Catherine are very keen to do the school run.
"Lambrook is very much sports-focused and all three children do love their sport.
"George, Charlotte and Louis are very excited about going to school together."
Perry has reportedly expressed his "delight" in the royal family joining his school.
"We are delighted that Prince George, Princess Charlotte and Prince Louis will be joining us this coming September and very much look forward to welcoming the family, as well as all of our new pupils, to our school community," reports The Sun.
