The pure white long-sleeved gown with a boat neck had been eagerly anticipated by royal fans around the world, with speculation over which designer would be chosen starting soon after the couple announced their engagement in November.
As the bride stepped out of her classic Rolls-Royce, Kensington Palace announced that Clare Waight Keller, who became the first female artistic director at famed French house Givenchy last year, had secured the coveted role of making the dress.
The 47-year-old, previously at Pringle of Scotland and Chloe, met Meghan earlier this year and the two worked together on the design, which "epitomises a timeless minimal elegance", Kensington Palace said.
"The focus of the dress is the graphic open bateau neckline that gracefully frames the shoulders and emphasises the slender sculpted waist," the palace said in a statement.
"The lines of the dress extend towards the back where the train flows in soft round folds cushioned by an underskirt in triple silk organza. The slim three-quarter sleeves add a note of refined modernity."
Edward Enninful, the editor of British Vogue, called the dress "beautiful" while bridal designer Raishma said the gown was "an example of couture design at its most classic and timeless".
"It was not a Cinderella choice, not one that spoke of fantasy or old-fashioned fairy tales, but one that placed the woman proudly front and center," Vanessa Friedman, fashion director and chief fashion critic at The New York Times, wrote.
"It underscored Ms. Markle’s own independence by divesting her of frippery, while also respecting tradition and keeping her covered up."
"It was simple and elegant," 23-year-old Emily Devaney from New Zealand said. "It's probably hard to dress for a royal wedding - you probably don’t have much you can go with but I thought she looked beautiful."
Nursing student Linda O’Dwyer said it was "very modern and classy" and she preferred it to the lace-embroidered gown Kate Middleton wore at her 2011 wedding to Prince William.
"It was like (Megan) didn’t want it to be too over the top with lots of embroidery. It really suited her style," she said.
However spectator Jennifer Hill, 69, described it as "very plain". "I’m not surprised but slightly disappointed," she said. "I thought it might be a little more flamboyant but it was very simplistic. I prefer her hair down.”
The well-kept secret over who would design the dress had kept royal fans and fashionistas guessing for months. Among those cited as contenders were labels Ralph & Russo and Burberry as well as designer Stella McCartney.
Waight Keller, whose name has now been catapulted into the global spotlight, described the chance to work on the historic occasion as "an honour".
"We wanted to create a timeless piece that would emphasise the iconic codes of Givenchy throughout its history, as well as convey modernity through sleek lines and sharp cuts," she said in a statement.
"Ms Waight Keller designed a veil representing the distinctive flora of each Commonwealth country united in one spectacular floral composition," the palace said.
Prince Harry last month was appointed a Commonwealth youth ambassador.
Queen Elizabeth lent the 36-year-old bride a historic tiara for the occasion. Made in 1932 for Queen Mary, the sparkling diamond and platinum bandeau has a centre brooch dating from 1893.
Meghan, now to be called the Duchess of Sussex, also wore Cartier earrings and bracelet, and silk duchess satin shoes.