The Queen’s granddaughter had a preview of the exhibition ahead of its opening to the public on Thursday.
Visitors will have a chance to see the Sir Norman Hartnell gown for the first time since she wore it for her secret wedding to Edoardo Mapelli Mozzi in July.
Made of ivory peau de soie taffeta, it was altered for Beatrice by the Queen’s personal adviser and dresser Angela Kelly and fashion designer Stewart Parvin.
It was first worn by the Queen to a state dinner at the British Embassy in Rome during a visit in 1961.
She also wore it to the world premiere of Lawrence of Arabia at the Odeon Leicester Square in 1962 and the State Opening of Parliament in 1966.
Footage from the world premiere of Lawrence of Arabia at the Odeon Leicester Square in 1962:
For Beatrice’s wedding, short sleeves of triple organza were added to the straps and embroidered with vintage diamantes to match the original design.
The full-skirted silhouette was also softened to give a more simplified shape.
The Royal Collection Trust said each alteration made to the dress is reversible to preserve the historic garment.
The display also features Beatrice’s Valentino shoes, which she also wore to the Duke and Duchess of Cambridge’s wedding in 2011, and a replica of her bridal bouquet made from artificial flowers has been created.
However, the Queen Mary diamond fringe tiara, which the Queen wore on her own wedding day in 1947 and was loaned to Beatrice, is not part of the exhibition.
Beatrice and Edoardo were originally due to marry in May in the Chapel Royal followed by a reception in the gardens of Buckingham Palace - but their wedding was postponed because of the coronavirus outbreak.
They eventually wed in a private ceremony, which was not made public beforehand, at the Royal Chapel of All Saints at Royal Lodge, Windsor on July 17 in front of just a handful of guests including the Queen and the Duke of Edinburgh.
Beatrice's father the Duke of York walked her down the aisle but notably did not feature in the photographs released by Buckingham Palace.
The special display of Beatrice’s wedding dress is part of a visit to Windsor Castle from September 24 to November 22.
The Royal Collection Trust welcomed visitors back to Windsor Castle, the Palace of Holyroodhouse, the Royal Mews at Buckingham Palace, and The Queen’s Galleries in London on July 23.
The charity has described the coronavirus pandemic as the “greatest challenge” in its history and predicted losses of £30 million over the next year because of the closure of its sites.