This morning, dusted off their formal wedding attire to prepare for their roles as page boy and bridesmaid, respectively, at their wedding of their second cousin, Princess Eugenie.
Arriving at St George's Chapel, Windsor, the pair looked adorable dressed in cream, navy blue and green.
Their appearance at the iconic Windsor location comes five months after the pair served in the same roles for at their royal wedding.
On 19 May, Princess Charlotte looked seriously cute in a puffy white dress designed by Clare Waight Keller (Givenchy's creative director who also created ), and ribbon-tied flower garland, whilst Prince George wore a mini version of Harry's formal frock coat.
Today, Charlotte is joined by hwe fellow bridesmaids - Zara Tindall's four-year-old daughter Mia, Princess Eugenie's goddaughter Maud Windsor, Robbie Williams' daughter Theodora, and Autumn Phillips's daughters Savannah and Isla.
Meanwhile, Prince George serves as one of two page boys on the day, joining Louis de Givenchy. Princess Eugenie was chosen to be Beatrice's Maid of Honour on the big day.
Last month the pair were spotted in similar wedding attire and at St. Andrew’s Episcopal Church in Norfolk.
The siblings should count themselves as experts when it comes to forming part of a bridal party. Just last year the pair had starring roles at the wedding of Pippa Middleton, the Duchess of Cambridge's younger sister, to James Matthews in May last year.
For the Berkshire wedding, Princess Charlotte looked sweet in a flowing white dress and pretty flower garland, as she threw petals outside the church.
Meanwhile, George looked adorable dressed in a Peter Pan collar shirt and olive-coloured plus fours, reacted with cream lace-up plimsols.