It’s not easy to out-dress a room decked in leopard-print carpeting, leopard-print walls and red velvet banquets. But on Thursday night the crowd managed to upstage the décor at the Nines, the piano bar and supper club in the NoHo neighborhood of Manhattan that is named for its address — 9 Great Jones Street — and its to-the-nines attitude.

The occasion was a party for the Attico, the six-year-old label by the Italian duo Gilda Ambrosio and Giorgia Tordini. Their over-the-top fashions are pure pleasure, bringing to mind a Champagne tower pour-over: indulgent and intoxicating, if a bit tacky.

At the Nines, the heiress Ivy Getty was swanning about in an off-the-shoulder catsuit scattered with a constellation of multicolored sequins by the Attico. The shoe designer Amina Muaddi shimmied through the room in a lime-green bustier minidress traced in black seams and cutouts. The DJ Kitty Cash posed for photos in a hot pink satin bra top and a green and black zebra-striped leather miniskirt.

By comparison, the influencer-turned-artist Nadia Lee Cohen looked tame in a lean leopard-print dress slashed across the torso. To show up in tasteful black was to feel like a cloud to the party’s silver lining.

Unless you were the disco legend Gloria Gaynor, who, a day after her 79th birthday, performed “Killing Me Softly” and “I Will Survive” in a custom-made black gown with feather-trimmed sleeves by the Attico.

The Attico’s founders, who have opened their first pop-up store on Wooster Street in SoHo, couldn’t help but represent the brand and its ethos better than their guests. Ms. Ambrosio, 30, wore a multihued sequin dress with cutouts and slits too complicated to describe succinctly as if she were born in it. Ms. Tordini, 37, looked disco-ready thanks to a prismatic, printed number.

The evening wear for which the Attico is known recalls various throwback goddesses — Cher in her Bob Mackie days, Bianca Jagger and Jerry Hall at Studio 54 — and yet manages to avoid feeling nostalgic or costumey. Dua Lipa, Rihanna and Beyoncé wear the Attico, and not just onstage.

On his way out of the party, Erik Maza, the executive style director of Town & Country, paid his respects to Stefano Marcovaldi, the Attico chief executive. “Congratulations,” he said. “You’re doing sexy very well in this new horny era we’re in.”

Yes, fashion at large has been gripped by a desire to bare all. Nipples, butt cheeks, midriffs are being teased and flaunted, framed and flashed in all manner of strappy, naked constructions. The Attico’s seductive designs stand out for their ability to tread the line between camp and chic. A feat, considering the ratio of bare flesh to feathers and sparkles.

How does something that could go so wrong feel so right?

“It’s the ultimate Italian style, which is glamorous but effortless and not too ostentatious,” said Ms. Muaddi, who met Ms. Ambrosio and Ms. Tordini in Milan a decade ago. “It’s fierce, it’s fun, it’s flirty. Young women, and women in general, want to feel like the girls and look like them when they go out.”

Before Ms. Ambrosio and Ms. Tordini introduced the Attico in 2016, they had separately amassed an audience as fashion influencers known during the first frenzy of street style. They teetered naturally between oversize Yeezus T-shirts and extremely baggy jeans, purple Prada shearling and miniskirts, silk gowns and Nike trainers.

Tall and lean with long hair, the two could be mistaken for sisters who both happen to wear clothes very well. Their personalities complement each other. Ms. Tordini says she’s introverted, though she did all the talking during an interview, while Ms. Ambrosio described herself as outgoing, open and daring.

They grew up around fashion. Ms. Tordini’s father owns a showroom in Milan; Ms. Ambrosio’s family has clothing stores in Naples. They studied fashion in Milan, started consulting for brands and became street-style stars and early influencers along the way.

As much as other brands liked sending clothes to Ms. Ambrosio and Ms. Tordini in their influencer days, they were intent on creating their own brand. They started plotting during a taxi ride between shows at New York Fashion Week in September 2015.

“We were just brainstorming about fashion and what we wanted to do,” Ms. Tordini said. “Like, what was missing, how we wanted to dress, what was the attitude, what was the woman that we were envisioning.”

It began with a single item: the robe, based on vintage styles they had found at Showplace, a vintage art, design and fashion market in Manhattan. They liked the idea of something that was sexy like lingerie but also versatile. It could be worn on its own, as a dress, or else as a jacket over jeans. They sketched a collection of 38 robes and slip dresses, imagining the world of their woman — where she lives, what music she listens to, what she reads, where she travels. The name was the last component.

“Attico means penthouse in Italian,” Ms. Tordini said. “It sums up this whole thing, and you envision immediately what it’s about.”

In 2016, they showed the Attico’s first collection at an apartment in Milan, staged and furnished with a retro Art Deco flourish. “It was chill,” Ms. Tordini said. “We were welcoming you to our house. Come, relax.”

At the time, Milan Fashion Week was a schedule of luxury heavyweights — Prada, Armani, Bottega Veneta, Dolce & Gabbana — that hadn’t changed in years. The sight of a new, independent label, especially one designed by women, was a breath of fresh air. So was their energy and attitude.

“Fashion images were not sexy anymore,” said Vito Fernicola, a photographer who has shot Attico’s campaigns. “When the girls launched, it was really colorful, sexy and back to fun and fashion.”

Net-a-Porter picked up the Attico’s first collection, along with nearly 100 other retailers. A year later, Ms. Ambrosio and Ms. Tordini were in talks with a potential investor, Pietro Ruffini. His father, Remo Ruffini, the billionaire fashion mogul behind Moncler, was funding a new investment vehicle, Archive Srl, and Mr. Ruffini was scouting potential fashion investments with his partner, Mr. Marcovaldi. The company took a 49 percent stake in the Attico.

“One of the main reason we invested was the potential we saw in getting away from the stereotype of the big, amazing luxury brands,” Pietro Ruffini said. “Also, I remember even before investing, many of the people I knew, all their girlfriends, were really considering the Attico when they had a big night out.”

The Attico woman is attracted to a kind of global glamour that has become familiar to Ms. Ambrosio and Ms. Tordini, whose time away from Milan includes frequent stops in New York, Las Vegas and Ibiza … a lot of Ibiza. Ms. Ambrosio’s boyfriend is Gabriele Simeoni, a partner in the club DC10 there.

“People travel from all over the world to go there,” Ms. Tordini said.

“On a Monday,” Ms. Ambrosio added.

The brand’s appeal is also steeped in fantasy. The Wooster Street pop-up is designed by Studioboom with wall-to-wall sage carpeting and matching floor-to-ceiling curtains upholstering the walls. Shoes and handbags are displayed throughout on a series of spiral staircases meant to epitomize the ethos of the Attico. The way to the penthouse is, as Ms. Ambrosio said, “going up.”