The royal brothers were spotted arriving at The Hunt and Polo Club in Memphis, Tennessee on Saturday evening for what was dubbed the "society wedding of the year".
William and Harry, who are believed to have acted as ushers on the day, were suited and booted in traditional wear for the ceremony. Harry, 29, looked particularly dapper in his morning suit, which he brightened up with a yellow jacket, while his older brother William, 31, coordinated with a maroon tie and grey pinstripe trousers.
Security was tight as the royals arrived for the nuptials. Black security cars circled the perimeter of the grounds and guards held back the throngs of people who had turned up in the hope of catching a glimpse of the high-profile guests.
All attention was soon turned on American bride Lizzy Wilson, the granddaughter of Holiday Inn founder Kemmons Wilson Sr., as she pulled up in a classic blue vintage car. The blushing bride wore a floor length white gown adorned with lace detailing. Lizzy had her hair swept up into an elegant chignon and fastened with a crown of white flowers to match her bouquet.
There was a brief moment of drama when Lizzy is said to have arrived at the same time as her future husband. Guy, holding out for tradition and not wanting to see his bride before the ceremony, went in ahead while Lizzy waited in the car.
The British nightclub owner and his hotel heiress fiancée wed in a romantic outdoor ceremony in the grounds of the Polo Club. Guests were seated on white chairs and enjoyed music by a choir of young boys, who had been heard practising Amazing Grace among other songs before the nuptials.
Following the ceremony, Guy and Lizzy were greeted by hugs and the sounds of cheers from William and Harry outside the venue. The royals' cousins, Princesses Beatrice and Eugenie, are also said to have attended the wedding.
The celebrations carried on with the reception at 8pm. A white marquee had been erected on the lawn of the Polo Club and the Jimmy Church Band kept guests entertained with their Motown hits by The Supremes, Marvin Gaye and Stevie Wonder and more contemporary artists including Ke$ha and Katy Perry.
As the couple's nearest and dearest danced the night away and feasted on a lavish dinner, they finished off their meal with slices from the impressive six-tiered wedding cake, which featured doves on the top and edible flowers flowing down the sides.
On Friday afternoon, William, Harry and other guests attended a pre-wedding reception at The Memphis Country Club. The royals were spotted mingling with other invitees and strolling through the luscious green grounds of the estate.
Sunday will see the final day of celebrations with the bride and groom hosting a sumptious brunch at the club.