“Twenty people can fit on that sofa,” says Ken Fulk, pointing out the emerald Edward Wormley number that snakes across a seating area in his airy new Tribeca loft. “It’s a party sofa if there ever was one.”

This piece and more party-perfect furnishings fill the Manhattan outpost of the San Francisco–based interior designer and event planner. “It really blurs the line between work and play,” he says of the apartment, where he will live, meet with clients, and, of course, entertain. “I never really wait for the weekend.”

And why should he? For Fulk, work looks a lot like play. Just thumb through his new book, Mr. Ken Fulk’s Magical World (Abrams), for a peek inside some of the elaborate homes he has devised for Bay Area tech giants and entrepreneurs and a look at the Battery, a five-level private club he helped conceive. The book also offers a tableside view of some of the wild parties that have made him famous. In a nod to Truman Capote’s legendary black-and-white ball, he once hosted a masked affair where socialites and Silicon Valley magnates rubbed elbows with drag queens and leather daddies. For Napster cofounder Sean Parker’s woodland wedding, he draped shimmering streamers from the oldest redwoods in California. A counterpart to his four-story base of operations in San Francisco—dubbed the Magic Factory—the New York spot will provide a stylish anchorage from which Fulk can conduct business on the East Coast. It will also serve as his next great party palace.

Fulk, who bought the space late last year and had things up and running by April, is quickly making friends with his new neighbors, including fashion photographer Bruce Weber upstairs. “If you want to spot cute girls and boys—and every once in a while a golden retriever—just buzz that elevator,” he quips.

While the 5,000-square-foot loft was generally as free-flowing as you’d expect, the kitchen needed to be opened up a bit, notes Fulk, who plans to host more dinner parties like Sunday Supper, a buffet for 50 friends he recently threw with chef-restaurateur Mario Carbone. In the sleek redo, matte-black cabinets conceal vintage glassware, 19th-century silver, and flea-market china, all of which fascinates the designer. “I love the idea that in 1956 someone may have had a glamorous dinner party with it,” he says.

In addition to remodeling the kitchen, Fulk put in a second bedroom and brought the bathrooms up to date. “The whole place looked like a party pad from 1978—there were even disco balls hanging from the ceiling,” Fulk reveals. “I’m sure some things happened here,” he adds with a raised eyebrow. And—almost certainly—the latest iteration will bear witness to a new era of high jinks.

In the loft’s kitchen, brass luggage corners outline the sleek black cabinetry.

Fulk, who started clipping flowers for his family’s dinner table at age seven, combines dahlias, garden roses, and pokeberry in a mercury-glass vessel.

“I feel like I’m shopping every morning,” says Fulk of the 1920s haberdashery cabinets where he stows his wardrobe.

The master bedroom features graphic linens by Ralph Lauren Home .