They're a family of three! The Duke and Duchess of Sussex introduced their firstborn child, baby Archie Harrison Mountbatten-Windsor, to the world on Wednesday, and Duchess Meghan looked lovely in a white trench-style dress by rising British designer Grace Wales Bonner for the momentous photo op.

The new mom was all smiles in the sleeveless double-breasted, tea-length frock accented with tortoise buttons and a tie-waist detail, Time reports, staying true to her penchant for trench-inspired dresses. She completed the look with beige pumps and delicate jewelry.

Meghan Markle and Prince Harry proudly display their son, currently known as Baby Sussex. The royal baby was born May 6. (Getty)

Though some outlets initially reported the sweet outfit was by Givenchy, reps for Wales Bonner confirmed to Fox News that the look was by their label.

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Meghan Markle and Prince Harry showed off their royal baby, known as Baby Sussex, two days after his birth. Queen Elizabeth II and Prince Philip (Getty)

A 2014 graduate of the esteemed Central Saint Martin, Harper’s Bazaar describes Wales Bonner as a rising star in the fashion world. The designer has previously collaborated with Jaden Smith and Solange, and was just announced as a 2019 finalist of the British Fashion Council's Designer Fund – winning $130,000 for her company – earlier this week.

Meghan Markle and Prince Harry's son made his debut on May 8. The child's name has yet to be revealed. (Getty)

“Born in Southeast London to a Jamaican father and English mother, Wales Bonner uses her mixed-race heritage as a key reference in her collections,” Business of Fashion writes of the up-and-comer. “Her work explores representations of black male sexuality and identity, through exceptional craftsmanship and embellishments.”

As of press time, Duchess Meghan’s trench dress does not appear to be available to shop online.

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Meghan Markle and Prince Harry debuted Baby Sussex, but didn't reveal the child's name. Their son was born on May 6.

Duchess Meghan, 37, and Prince Harry, 34, first introduced their son on May 8 outside of their Windsor Castle home, elated at the birth of Archie Harrison.

"It's magic! It's really amazing. I have the two best guys in the world, so I'm really happy," the new mom said of her growing family.

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The royal continued to gush that the baby boy has the "sweetest temperament," revealing that he's "really calm."

"It's just been a dream. It's been a special couple of days," she said.

"Parenting is amazing. It's only been, what? Two and a half days, three days? But we're just so thrilled to have our own little bundle of joy," Prince Harry agreed. "We're looking forward to spending precious times with him as he slowly, slowly starts to grow up."

Fox News’ Jessica Sager and the Associated Press contributed to this report.