Most Rev Justin Welby will join the Duke and Duchess of Cambridge and Prince Harry on 1st July for the ceremony at her family home, Althorp House.
In a brief statement, Kensington Palace said: "The service, which will fall on what would have been the Princess's birthday, will be conducted by The Archbishop of Canterbury and attended by her family."
The service is planned to take place less than two months before the 20th anniversary of Diana's death. William was 15 and his brother Harry was twelve when their mother was killed in a car crash in Paris on 31st August 1997.
To mark the anniversary, the royal brothers are commissioning a statue to stand in the public gardens of her former home, Kensington Palace in London.
Meanwhile, the Diana Award charity - created to celebrate the Princess's faith in the potential of young people - has embarked on a year-long series of events.
It is understood Prince George and Princess Charlotte will also join Archbishop Justin at the re-dedication service, as will Diana's brother Earl Spencer.
The Earl Spencer's wife, Countess Spencer, has been behind a redesign of Diana's resting place - an island in Oval Lake with Althorp Park's Pleasure Garden.