On the day of our interview in Florence, a sweltering midsummer afternoon, the designer Gioia Bini called to say she was running about an hour late. I figured I’d kill the time with a coffee at the train station (my idea, I had just arrived from Rome), but she insisted I go straight to her family’s home on the banks of the Arno. “It’s too hot to be outside,” she said. “Ring the bell three times, and the housekeeper will let you in.”

A little while after I’d settled down at the kitchen table with my laptop, she arrived, wearing a pale-blue linen shirtdress of her own design (artfully rumpled, sleeves rolled up), hair windswept because the A/C was broken in the old Fiat Panda she’d been driving, skin tanned from a week in Amalfi with her cousins. Today, it turned out, she had been in Arezzo, visiting her 87-year-old tailor, who was making her a couple of suits for the fall.

If everything about this encounter sounds almost comically Italian to you, I get it. But it’s that combination of warmth, informality, effortlessness, and a total dedication to getting clothes just right that Bini can credit for the success of her eponymous brand.

The “Lucinda” macramé-lace maxi dress.

She spent her early childhood in Niger, where her mother was writing a thesis on African art, before moving to Florence when she was three years old. After stints as a model, assisting Bruce Weber’s creative director, working with Lisa Immordino Vreeland to produce documentaries on Peggy Guggenheim and Diana Vreeland, and working at Moda Operandi, Bumble, and the furniture-and-décor company Artemest, Bini decided life in an office wasn’t what she wanted: “I need to be on the go. I need to be constantly running around, looking, touching, seeing stuff,” she told me, while sprawled on an overstuffed sofa in a study that looked out onto the river. So, she moved back to Florence.

The brand started organically three years ago, after Bini grew frustrated with spending too much on dresses from big-name designers that were using materials she describes as “highly flammable.” So, she walked around the city, found some fabric and a seamstress, and made her own. (While Milan is Italy’s more well-known fashion capital, a lot of clothing and textile production happens in Florence and the nearby Prato. One really can find world-class seamstresses and pattern-makers just by wandering around and asking the right people.) When friends started asking her for them, she bought 50 meters of linen and made her first batch of dresses: the ruffle-trimmed “Camilla,” with buttons down the front and a sweetheart neckline; the “Lucinda,” a minimalist maxi with a trim, simple bodice and a round skirt; and the “Emma,” a caftan-inspired shirtdress.

Gioia Bini (bottom left) surrounded by her designs, photographed among the Roman ruins of Paestum, on Italy’s Tyrrhenian coast.

Since those early days, she’s expanded her models and materials—making the Lucinda in a colorful macramé lace, adding the dirndl-inspired “Chiara” and the ladylike, crêpe “Carolina,” among others—but the brand retains the same essential DNA. “They’re very feminine, but that’s just because the dresses are so 1950s,” Bini said of her pieces, which are sold online on Web sites such as Matches Fashion and can be seen all over Instagram on the likes of Margherita Missoni and Giovanna Battaglia Engelbert. “They’re versatile yet elegant and really, really well made.”

While she produces her collection in Florence with luxury materials, she keeps prices sub-astronomical (between $300 and $1,000) by using scarti, or excess fabric, from brands like Loro Piana, which sell bolts of discounted linen and silk that aren’t big enough to use for their purposes. This also feeds into the sustainability element, which is important to her. “It hurts when I go into a store and see them selling something for 1,000 euros, and I touch it and it’s polyester,” she said. “Polyester is plastic.”

Bini hopes the future of fashion, and of her brand, will look a bit more like the past. She’s working on building her Web site, where she’ll have an archive of models that customers can have made to order in the fabric of their choosing. She thinks of the days when her grandmothers would go to Paris to have everything tailor-made. “People were making things for themselves. And that’s kind of what inspired me, because I was making it for myself. I really wasn’t into fashion,” she said, at least not in the traditional sense. “It was really more about the beauty.”

Andrea Whittle is a writer living in New York City