For the past eight years, the interior designer Iris Dankner has held Holiday House, the design show she founded to benefit the Breast Cancer Research Foundation, at a historic mansion on the Upper East Side. “You sort of saw the same faces every year,” said the cancer survivor, adding that it was time for a change.

“She said to me, ‘I want to shake things up!’” recalled Jared Seligman, a top New York real estate broker, who subsequently found her two newly constructed adjacent townhouses downtown in Soho, and enlisted a new guard of talent — including himself — to outfit them. “It’s not just new decorators, it’s also visionaries,” said Dankner, referring in part to the fashion designer Brandon Maxwell, who adorned Ryan Korban’s dark, luxurious sitting room with mannequins wearing his gowns.

Fashion, as it turns out, has emerged has a prominent theme within the showhouse, which opens today and runs through January 8. Like Korban, whose first big project was decorating his shoe store Edon Manor, many of the participants started out not at traditional design firms, but rather in fashion, and it's evident in the rooms they’ve created.

Patrick Mele worked as an interior stylist for Ralph Lauren before starting his own firm in 2012. His space, a richly layered lady’s boudoir complete with lavender cotton upholstered walls and a Chinese deco carpet, was inspired by the work of fashion illustrator Kenneth Paul Block. “I was trying to evoke that 70's Parisian world of Diana Vreeland and Sao Schlumberger,” he said.

Next door, Patrick McGrath, who worked at Armani before starting his own company last year, created an elegant gentleman’s dressing room using an 18th-century daybed procured at Christie’s, Loro Piana cashmere curtains, John Currin etchings, and an Hermes valet that once belonged to Jacques Grange. “It’s sort of a mix of everything,” he said.

For her part, Sasha Bikoff, whose m.o. is reupholstering antiques in remnant fabrics from the runways, has fashioned a whimsical flamingo-pink dining room with French Empire chairs in a Pucci silk and a Pierre Cardin lacquered sideboard. Many of the items on display are available on her website and 1st Dibs.

“This is a place where designers can really be creative,” said Dankner. “And I love that most of them went out of their comfort zone.”