Markle, now known as the Duchess of Sussex, first wore a wedding gown, made out of triple silk organza, featuring an open bateau neckline with three-quarter-length sleeves.
Her look, which was seen by millions watching around the world, was completed by her "something borrowed" -- Queen Mary's diamond bandeau tiara, which Queen Elizabeth loaned to Markle, complete with a flower-outlined veil that measured at 16 feet long.
Clare Waight Keller, the first female artistic director to head the house of Givenchy, said in comments to the press just what the groom thought of his bride's look.
"He came straight up to me and he said, 'Oh my God, thank you! She looks absolutely stunning,'" Waight Keller, 47, recalled. "Well, I think everybody saw on television -- he was absolutely in awe, I think. She looked just incredible and it showed.
"So I think for the both of them, they were just radiant at that time," she added.
Keller, who accompanied Markle on her wedding day, also shared just what her role entailed.
"The moment they stepped out as the Duke and Duchess of Sussex," she began, "I was standing just inside making the final adjustments to the beautiful 5-metre veil before they descended the steps to their carriage."
The Duchess wore a silk crepe, floor-length gown with a high collar, according to Women's Wear Daily, which released sketches of the dress Sunday. Markle completed her look by wearing "something blue" -- Aquazzura satin shoes with baby blue soles.
“I am so proud and honored to have been chosen by the Duchess of Sussex to make her evening gown and represent British design," McCartney, 46, told the magazine. “It has truly been one of the most humbling moments of my career and I am so proud of all the team on this stunning sunny royal day.”
The designers' comments about their memorable designs came as Kensington Palace released never-before-seen sketches of Markle's first wedding look.
"The Duchess and Ms. Waight Keller worked closely together on the design, epitomising a timeless minimal elegance referencing the codes of the iconic House of Givenchy," the palace added in a tweet.