Nearly a decade ago, when Precious Lee arrived for a modeling go-see, she was grilled about her ethnic background. The clients, who were representing a deep-pocketed luxury brand, were looking for a mixed-race model, Ms. Lee recalled. When she told them that she was Black, their faces fell.

“Oh, you’re just so pretty,” they raced to reassure her. She was as quick with a comeback.

“I didn’t know being Black didn’t come in pretty,” she said.

Fast-forward a few years to find Black models making token appearances in fashion campaigns as part of a multicultural mix. “The typical casting was one Black model and one Asian,” said Alton Mason, a Black model who has been prominently featured in campaigns for Etro, Missoni and Tommy Hilfiger. “The rest of the models were white.”

Times change. A health crisis combined with a summer of civil unrest and protests against racism has forced a shift in mindset. Magazine editors reacted, enlisting high-profile Black personalities — among them, Rihanna for Harper’s Bazaar, Cardi B for Elle and Kerry Washington for Town & Country — to front their September issues.

But advertisers have been at least as swift to seize the moment.

“People got woke in the middle of this,” said Kenneth Richard, the creative director and chief executive of The Impression, an online fashion magazine.

Models of color had already bowed in some campaigns, a nod in part to the widening influence of Black artists, thinkers and athletes on the popular culture. “But it took a big social awakening to really expedite things,” Mr. Richard said.

As a social corrective, the movement is gathering steam.

The pandemic hampered efforts by The Fashion Spot, an online publication that tracks diversity in the industry, to collect an official tally this year, but the numbers reported last fall showed Black models represented by an increase of one or several percentage points at the publications it tracks, according Morgan Schimminger, a contributing writer and editor.

“The assumption would be that the move toward diversity will continue in that direction,” Ms. Schimminger said.

In the light of the latest campaigns, that forecast seems conservative. These days models of color are virtually omnipresent in leading style publications.

During lockdown, Pierpaolo Piccioli, the creative director of Valentino, unveiled “Empathy,” a campaign that harnessed the star power of “friends of the house,” notably Laura Dern and Gwyneth Paltrow, Naomi Campbell and the Sudanese-Australian fashion star Adut Akech.

J Brand, the Los Angeles jeans label, captured the newcomer Oumie Jammeh posing languidly in a field of wildflowers; Fendi released a print campaign and short film featuring the singers, and sisters, Chloe x Halle, both demurely garbed in puff-sleeve frocks.

Even the formerly recalcitrant Hedi Slimane, the creative director of Celine, performed an about-face. Called out for excluding Black models from his runway and Instagram account, Mr. Slimane cast the neophyte Essoye Mombot, shooting her in St.-Tropez for his fall campaign.

Spurred by the crisis, Michael Kors sought a more novel approach. “We decided that it would be exciting to bring the energy and electricity of our backstage show environment to our campaign and the consumer,” he said. His fall 2020 campaign, featuring the sought-after Nigerian model Mayowa Nicholas and Annibelis Baez, who is Dominican, stars in what Mr. Kors, echoing a popular new marketing phrase, calls “a United Nations of Beauty.”

Top agencies have been no less aggressive in pushing for inclusion. “We are actually making calls, talking to clients and giving them direction,” said Ivan Bart, the president of IMG Models. “We’re telling them, ‘We understand what you want, but if you want to stay relevant, this is what you need.’”

Brands are heeding the call, even if their motives are sometimes open to question. We may well see a substantial rise in Black models’ visibility, said David Lipman, a veteran creative director whose clients include John Hardy, the jeweler, and Naked Cashmere. “But I hope it’s not a temporary cover-our-base uptick,” he said.

Some brands may be thinking defensively, their reactions to Black Lives Matter often based on fear, Mr. Lipman noted. “They’re afraid of Diet Prada outing them,” he said, referring to the influential Instagram account and industry watchdog that has called out Dolce & Gabbana and other industry players for racism.

And for some, casting Black models has clearly been an afterthought, Mr. Richard said. “When you see a narrative that was clearly built around a white couple, and you suddenly see a third person hanging around, that seem seems forced.”

Diversity in casting has, not incidentally, spawned a roster of newcomers being actively groomed for the kind of celebrity once enjoyed almost exclusively by Tyra Banks, Ms. Campbell, Tyson Beckford and their high-profile ilk. Maty Fall, a 19-year-old Senegalese-Italian university student, caught marketers’ attention after appearing on the cover of Vogue Italia last year. But Ms. Fall, who has since starred in campaigns for Pat McGrath Labs, Etro and Dior, views her success with a gimlet eye.

“I can’t honestly say that the casting of more people of color is an act or if it’s genuine,” she said. “I don’t want this to be just a trend. But we all know that the fashion industry is very unpredictable.”

The industry’s track record has hardly been unblemished. “Until a few years ago, advertising was very conservative,” said Trey Laird, the founder and chief executive of Laird+ Partners, whose clients include Tom Ford, Tiffany and Co., Topshop and Jimmy Choo. “People were making safe choices, relying on the bourgeois appeal of a beautiful blond woman with glossy red lips.

“We were going by old rules that have little to do with the way the world works. It was like fashion was talking only to itself.”

A dozen years ago, Italian Vogue tried a more far-reaching statement with an all-Black issue. A radical move, much applauded at the time, it raised eyebrows just the same.

Black models had taken over the magazine’s editorial pages. “But in the ads, all of the models were white,” Bethann Hardison, a former model and agent and an industry gadfly for diversity, recalled.

More recently, once-reluctant luxury brands have embraced diverse casting as a sound commercial strategy. “Brands have discovered that when people see models of color, that will not keep them from buying,” said Ms. Hardison, who heads a diversity program for Gucci. “Years ago, they thought it did.”

Mixed casting also reflects a pronounced shift in brands’ consumer base. “We’re not living in silos,” Mr. Laird said. “Fashion is global. Valentino is no longer just an Italian brand. The woman in Shanghai, Dubai and on Madison Avenue, they all may be Valentino customers.”

Brands courting those customers have raced to keep pace with a culture that venerates Beyoncé, whose musical film “Black Is King” has fired the pop imagination, and Michael Jordan, the focus of “The Last Dance,” a documentary that follows the rise of the Chicago Bulls and the lead-up to Mr. Jordan’s final season.

But real advances, some suggest, will occur only when people working behind the scenes have a voice in determining who gets a star turn in front of the camera. “This is not just about diversifying the talent,” Mr. Bart said, “but about asking who are the casting directors, the creatives doing the hair, the stylists, the photographers?”

Two years ago, Vogue signaled a swing in direction, assigning a 23-year-old Tyler Mitchell, the first African-American to shoot a Vogue cover, to capture Beyoncé for its September issue. That move roughly coincided with significant changes in fashion’s top echelons.

A year earlier, Edward Enninful, a Londoner of Ghanaian descent, had been named the editor of British Vogue. In 2018, the African-American Virgil Abloh was named artistic director of the Louis Vuitton men’s wear line. This summer Samira Nasr, a woman of Lebanese-Trinidadian heritage, became the editor of Harper’s Bazaar.

“I feel a great sense of urgency,” Mr. Bart said. “This can’t be just a passing moment.”