The Duchess of Cambridge’s sister is to wed her financier boyfriend James Matthews at St Mark’s Church, Englefield, Berkshire, on the morning of Saturday May 20.
Kate will be accompanied by the Duke of Cambridge and Prince Harry at what is set to be one of the most talked about society weddings of recent times.
The palace said George and Charlotte will be in the bridal party.
Royal watchers were expecting the young royals to play an important role at the wedding with speculation Kate would be her sister’s matron of honour.
Hedge fund boss Mr Matthews got down on bended knee during a trip to the Lake District in July 2016 to propose to Pippa.
The couple had been dating for less than a year, but had moved in together and Pippa was said to have been totally surprised by the proposal.
Pippa leapt into the public consciousness in 2011 when she was her sister’s bridesmaid in a figure-hugging Alexander McQueen dress at the royal wedding.