The only non-royal bridesmaid will be Theodora Williams - the six-year-old daughter of Robbie Williams and Ayda Field.
Tom will take up the role in St George's Chapel in support of his brother as he marries Princess Eugenie in front of a worldwide audience.
Princess Beatrice, 30, will act at Princess Eugenie's, 28, maid of honour on her sister's big day.
Kensington Palace confirmed the members of Eugenie and fiance Jack Brooksbank's bridal party on Wednesday, ahead of their big day on Friday. New reports say that even though the entire royal family will be there - including Eugenie's parents Prince Andrew and his ex-wife Sarah Ferguson - Camilla is being forced to skip the ceremony and reception.
The wonderful news was made public on Wednesday (Oct. 9) when an official statement was published to the Royal Family's official website and then shared on Prince Andrew's official Twitter page. Princess Eugenie and Mr Brooksbank met at the Swiss resort of Verbier where Eugenie was on a family vacation celebrating her father's 50th birthday.
In addition to fulfilling her royal duties and supporting a number of charitable organizations, the princess works in the art industry. Princess Eugenie is godmother to Maud.
The Buckingham Palace announcement comes two days before the couple's Windsor wedding.
Ten-year-old Viscount Severn and Lady Louise Mountbatten-Windsor, 14, will also be part of the wedding as special attendants.