TONY KING CAN recall an irksome time, some years ago, when he would constantly swap his Church’s dress shoes for a more comfortable pair of Converse All-Stars throughout the workday, depending on whether he was leading an important meeting or overseeing a relatively laid-back photo shoot. “I was always changing,” he said.

That stopped around 2008, when Mr. King, 43, bought his first pair of Common Projects leather sneakers. Suddenly, the CEO and creative director of New York-based digital agency King & Partners, whose clients include 3.1 Phillip Lim, could leave the house in a single pair of shoes appropriate for pitching new business or heading out for Peronis. Bonus: They encased his feet so painlessly he could walk anywhere.

“It was a socially and professionally acceptable sneaker that looks more like a shoe but is comfortable like a sneaker,” he explained. In other words: A size-10 Holy Grail. Though he still pulls out his Church’s for “very smart meetings,” he mostly lives in sneakers and owns around 20 pairs of Common Projects, in various styles, materials, colors and states of wear.

Mr. King is hardly alone in discovering that high-end, designer sneakers can constitute a crucial part of the modern menswear wardrobe. While Masters of the Universe still dutifully pair their Super 100s suits with proper leather lace-ups, other men in offices nearly as formal routinely pad around in upscale rubber-soled shoes. My own once-beloved wingtips are gathering dust, forsaken for a pair of Adidas Stan Smiths made in collaboration with Belgian designer Raf Simons.

Luxury sneakers now dominate men’s footwear sales for e-commerce site Mr Porter and department store Barneys New York. In a telling move, the latter recently combined the formal and casual shoe departments at its New York and Beverly Hills locations. (“Did we really need to separate the John Lobb guy and the Louboutin guy?” asked Tom Kalenderian, the store’s executive vice president of men’s, referring to consumers of traditional dress shoes and those seeking designer Christian Louboutin’s studded sneaks.)

Still. Designer. Sneakers. As recently as five or six years ago, those words together still conjured an off-putting image for many men—of over-designed, gallingly expensive footwear, littered with logos in a way that evoked a duty free shop. The sort of thing a respectable guy wouldn’t be caught dead in.

The First Time Ever I Saw Your Lace 1. Z Zegna Techmerino Racers, $395, zegna.com; 2. Sneakers, $720, prada.com 3. Sneakers, $625, Tod’s, 212-644-5945; 4. Adidas by Raf Simons Stan Smith Sneakers, $455, adidasx.com; 5. Calfskin and Neoprene Sneakers, $795, Balenciaga, 212-226-2052; 6. Givenchy Sneakers, $595, Bergdorf Goodman, 888-774-1855 Photo: F. Martin Ramin/The Wall Street Journal, Styling by Anne Cardenas

How did we get here from there? A confluence of factors are at play. First, dress codes have become increasingly relaxed over the past decade—remember when sneakers weren’t allowed in night clubs?—allowing for more creativity and freedom. Second, as designer-sneaker sales have ticked up and the shoes’ 24/7 relevance has somewhat justified the price, more designers have begun paying attention to the market.

Though luxury brands have been making sneakers since the advent of Gucci’s tennis shoes in 1984, Mr Porter buying-and-sales director Toby Bateman credits both Common Projects, which launched in New York in 2004, and French label Lanvin with legitimizing the category. Lanvin’s slim-soled tennis-style sneaker with a patent leather toecap, introduced in 2006, moved the needle in the luxury world, he explained: “Everyone embraced it because it was wearable. It didn’t look like you were wearing running sneakers with your suit or smart trousers. That led to a lot of other people entering the arena.”

That includes folks you’d assume would sniff at the very idea of sneakers. Tom Ford—who launched his menswear label with stores staffed by butlers and uniformed maids—now makes several styles of sneakers, ranging from $790 to $1,090. This spring, venerable footwear brand Berluti also launched sneakers, all priced over $1,000, some in suede and others in its signature burnished patina leather.

Italian maker of the ne plus ultra in cashmere, Loro Piana, has low-key velvety suede running shoes for $925. “If I went back five years in time and said to the guys at Loro Piana, ‘I predict in five years, you’ll have a suede running shoe,’ they would have laughed me out of the showroom,” said Mr Porter’s Mr. Bateman.

“ When a guy gets that level of comfort and style, it’s hard to get him back into shoes. ”

Now there’s a sneaker for every man—no matter his aesthetic. “You don’t need to be wearing a pair of drop-crotch sweatpants to be wearing [designer] sneakers,” said Barneys’ Mr. Kalenderian. “You can wear them with a gorgeous suit and look like a million bucks.”

Some, more controversially, even pair them with a tuxedo. Bally design director Pablo Coppola, who said he no longer wears dress shoes at all, donned sneakers for this year’s Costume Institute Gala at the Metropolitan Museum of Art, arguably Manhattan’s most prominent social event. When in formal clothes, he said, “wearing sneakers is a way of dressing it down a little bit.” Michael Schulson, Philadelphia-based chef and owner of restaurants Sampan and Graffiti Bar, also advocates sneakers with a tux. “I have a black-tie event next week and I’ll probably wear a pair of Lanvin’s or Cipher’s Parallax [style],” he said. However, he added, “certain people can pull it off, certain people can’t. It’s not for everybody.”

To return to those galling prices, some men will invariably argue that it’s ridiculous to pay, say, $545, for Saint Laurent’s SL/01 Court Classic sneakers, which look a fair amount like Adidas’s classic Stan Smiths that cost around $75. But most designer sneakers are made with Italian leather on par with that used for dress shoes, hide that tends to look more refined and last longer than the leather of mass-market versions. And while they might take cues from more affordable styles by Nike or Adidas, their upgraded air gives them entree where cheaper sneakers wouldn’t dare tread.

Athletic brand “sneakers look so ragged after a couple of weeks,” said King & Partners’ Mr. King. Designer versions feel nicer for longer, he added. “And they make me look a bit more dressed up, like I put more effort in than [just lacing on] a pair of Converse.”

Will the designer sneaker trend soon run out of steam? Perhaps. But if there’s a single factor cementing its place in menswear, it’s comfort. “No matter what happens with fashion,” said David Sills, men’s creative director at Hirshleifer’s department store in Manhasset, N.Y., “when a guy wears sneakers and gets that level of comfort and style, it’s very hard to get him back into shoes.”

Mr. Sills has put his money where his mouth is, recently unveiling an area in the store made of Carrera marble, steel and glass that’s dedicated to sneakers — “a temple to the category,” he said. And the retailer himself has swapped his stiff-soled Aldens for a pair of Yeezy Boosts, the sneakers from the high-end collaboration between Adidas and Kanye West. “You can wear them everywhere,” he said. “Every restaurant, every event.”