INDIO, Calif. — It was just after 1 a.m. and Jeremy Scott, the forever young fashion designer, held court in a wooden D.J. booth above a synthetic grass dance floor. His annual party, timed to the Coachella Valley Music and Arts Festival, was just starting.

Over the next few hours, Kylie Jenner, Jared Leto and Diplo would come through, but at that moment Mr. Scott beamed and bounced as if on a tiny trampoline, hugging friends and scanning the crowd for standout looks. He snapped a photo of Katy Perry, who wore a baby blue guitar dress from his fall 2016 collection.

“I just wanted to have this feeling of when I am on the fields, and the mix of clothes,” said Mr. Scott, 40, who wore a studded-leather suit of his own design. “Sometimes there are things that are a little more flamboyant and things that are a little more utilitarian. It 100 percent translated directly to a whole collection.”

Unlike fashion brands that have glommed on to Coachella as a marketing opportunity, Mr. Scott, the creative director of Moschino, comes to the festival to see, sketch and get inspired.

The Coachella look, as anyone who has recently scrolled through Instagram knows, revolves around crop tops, see-through slips of fabric and fringe galore, all of which Mr. Scott has reinterpreted with flower-power colors, cartoonish prints and a cheeky sense of humor.

“I’m very organic in nature with my creativity,” he said. “It just kind of wraps around me, or it’s a moment I have, a click of inspiration. It’s never calculated.”

And while he’s at it, he’s also having a good time. “Give it a little bit, because it’ll get wild by 3 a.m.,” he said, shouting over thumping music. How long did he plan to stay? “Forever, till it’s no more fun.”

Mr. Scott’s immersion into Coachella began with Bjork. “I had just moved to L.A., and she was like, ‘Come to this music festival. I’m performing,’” he said, the day before his party, lounging in a house in Rancho Mirage, Calif., that he had rented. “I had no idea. It was also still in its infancy.”

Bjork was also responsible for Mr. Scott’s treating Coachella as a fashion incubator. In 2007, when she headlined again, Mr. Scott dressed her in a hair-fringed corset dress printed with pictures of bones. “With the clothes I design, I think about my friends, how I’d want them to dress, what I’d want them to wear,” he said.

He has created looks for other Coachella performers as well. In 2010, Beth Ditto wore a black shift dress of his with stained-glass-like accents. In 2014, Rihanna wore leopard print sneakers he designed for Adidas. And last year, Madonna strutted on stage with Drake in a Moschino dress printed with cartoonish jewels.

Inspiration flows the other way, too. Mr. Scott said his spring 2015 collection, a riot of baby-doll dresses in psychedelic swirls, was a homage to Coachella. A candy-colored headpiece, which Miley Cyrus helped design, evoked the flower crowns once favored by young women at Coachella. (Brimmed hats were more abundant this year.) Likewise, festivalgoers inspired the Daisy Duke-style gold hot pants and a multicolored plaid shirt tied above the navel that he sent down the runway.

Men also served as muses. One male model wore gold pants, orange combat boots and a yellow sweatshirt tied around his waist, a look ripped straight from the desert fields. “I just love the mix of the way things are worn,” Mr. Scott said, pointing to the plaid shirt tied around his midsection.

Mr. Scott is not the only fashion designer to find inspiration at Coachella. Alexander Wang frequently attends, as does Hedi Slimane, the former Saint Laurent creative director. But Mr. Scott’s status as Coachella’s reigning designer was solidified in 2008 when he started his own party on the first Saturday night of the festival.

What began as a gathering of up to 100 friends at a rented estate in Palm Springs, Calif. (one that once belonged to Frank Sinatra), has grown into one of the festival’s hottest tickets. This year, Mr. Scott moved the invitation-only party to the Corona Yacht Club, a 20-acre tree-shaded estate in Coachella, the town. While it doesn’t have any boats, it does have a two-acre lagoon — and no neighbors who might complain.

“We can be later and louder,” Mr. Scott said. “It’s nicer than having to try to damper the party at two in the morning.”

His was not the only party of the night. In recent years, the number of fashion brands holding events at Coachella has ballooned. This year, H&M was an official sponsor of the festival. Calvin Klein hosted a “brand experience” event that featured top-tier D.J.s at a warehouse plastered with its logo.

Mr. Scott brushed off these efforts as “inauthentic.” “I think it’s funny because a lot of them don’t have an organic connection to it, so it’s kind of an odd fit,” he said. “I don’t really care because I’ve owned the Saturday night slot now since, like, a decade. It’s my party night, and everyone knows that.”

When Mr. Scott isn’t at a party, he relaxes and tries to channel his ideas into sketches. This year, he and 10 friends took over a 6,300-square-foot Rancho Mirage house once owned by former President Gerald R. Ford and his wife, Betty.

On the Friday afternoon before his party, Mr. Scott could be found padding over the silk shag carpeting in faux-denim pants, a cutoff Batman T-shirt and a plaid shirt tied around his waist. Out by the pool, four well-toned young people splashed around in swimwear made by their host. Beneath an umbrella, a buff man smeared sunscreen on the areas not covered by black-and-gold Moschino bathing trunks.

“Isn’t it so beautiful out here?” Mr. Scott asked. “Just the quality of the light. Sometimes when I’m just really relaxed, that’s also a creative time for me, because that’s when my mind is more open, because I’m not worried or thinking or being very analytical.”

There was no sketching at that moment, but “when you’re feeling at ease and relaxed, a lot of ideas flow,” he said.

Let the other fashion brands have their hashtagged events and millennial outreach. “In general, I just kind of live,” he said, his voice drifting off as he watched his friends frolicking in the pool. “I’ve become a little bit more of a lounger here. It’s Coa-chill-a.”