It was a royal family affair!

Lady Gabriella Windsor and Thomas Kingston tied the knot at St. George's Chapel in Windsor Castle on Saturday, with many royals, including Prince Harry, Queen Elizabeth II and Prince Philip, in attendance.

Lady Gabriella is the 38-year-old daughter of the queen's cousin, Prince Michael of Kent. Her wedding comes almost one year after Harry and Meghan Markle said their "I dos" at the same location. The stunning bride looked radiant in a custom-made lace wedding dress by Luisa Beccaria, which was embroidered with flowers and embellishments. She donned a long tulle veil and wore a diamond tiara that her grandmother, Princess Marina, Duchess of Kent, and her mother, Princess Michael of Kent, wore on their wedding days.

New dad Harry, who was reportedly not expected to attend, made a surprise appearance at the wedding. The 34-year-old royal sported morning dress attire, consisting of striped trousers, a blue waist coat, white shirt, baby blue tie and morning coat.

Harry -- who welcomed his firstborn son Archie earlier this month -- was all smiles as he gathered around his family.

Queen Elizabeth wore a bright pink coat and white floral dress for the occasion, while Philip looked dapper in his black morning coat, dark trousers and gray waistcoat.

Also in attendance was Kate Middleton's sister, Pippa Middleton, and her husband, James Matthews. Pippa arrived in a light blue velvet Jess Collet Milliner dress with matching headband and heels.

Princess Anne, Prince Edward, Prince Andrew and his ex-wife, Sarah Ferguson, were spotted arriving to the chapel, as well as Princess Beatrice and her boyfriend, Edoardo Mozzi.

On Sunday, Harry and Meghan will be celebrating their one year wedding anniversary. The couple, who welcomed baby Archie on May 6, has been enjoying every part of parenthood in the past weeks. While Harry has had to attend a handful of royal events, the young royals have the help of Meghan’s mother, Doria Ragland, who flew to the U.K. from America ahead of the birth.

A source told ET that Doria has been "very hands-on" helping Meghan and Harry, who "absolutely adores" his mother-in-law, found it "very special" to spend Mother’s Day with her and his new family.

For more on Meghan and Harry's baby and their anniversary, watch below.

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