Joining three-year-old Charlotte will be Harry’s god-daughters Florence van Cutsem, also three, and Zalie Warren, two, Meghan’s god-daughters Remi and Ryan Litt, six and seven, and four-year-old Ivy Mulroney.
George’s fellow page boys are to be Harry’s godson Jasper Dyer, six, and Ivy’s brothers Brian and John, who are both seven-years-old.
Ivy, Brian and John are the children of Meghan’s best friend Jessica Mulroney, a Canadian fashion stylist, and husband Ben, who is a television presenter.
Kensington Palace said details about the girls’ dresses and boys’ uniforms would be kept under wraps until the event itself in Windsor on Saturday.
George and Charlotte had important roles among eight pageboys and bridesmaids at their aunt Pippa Middleton’s wedding to James Matthews in May last year.
On that occasion, George wore a cream top with gold breeches, cream socks and carried a confetti basket.
His sister wore a cream dress and had a heart shaped floral garland in her hair.
Their mother, the Duchess of Cambridge, had confessed that she had concerns about how her children would behave at the wedding, and she was spotted with a finger over her mouth to quieten them.
It is also thought George was told off by his mother outside the church.
The announcement from the palace came as the first pictures emerged of Meghan’s mother, Doria Ragland, making her way to the UK ahead of the wedding.
The 61-year-old is set to touch down at Heathrow on Wednesday amid growing speculation that she will be the one to walk her daughter down the aisle in Windsor, with ex-husband Thomas Markle reportedly set to miss the event after undergoing heart surgery.
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:: Sky News will broadcast live in Windsor the week before the royal wedding with all the build-up to the big day, with exclusive live coverage of the wedding in UHD in a special programme from 9am to 3pm on Sky News and Sky One on Saturday 19 May.