As the creative force behind Gucci's clothing and accessory collections, Frida Giannini is known in the fashion world for the way she draws inspiration from the Italian luxury brand's archives to create classic, wearable designs.

Much less discussed is how Ms. Giannini applies the same design philosophy to create new spaces. She designed Gucci's new flagship store in New York. (She heads there next week for a charity event; proceeds from the sale of a special collection of Gucci handbags will be donated to Unicef-run programs in Africa.) And her love of interiors is apparent throughout her eclectic-yet-thoroughly-contemporary 18th-century Italian villa, nestled in the hills above Florence.

"Architecture and interior design are my second passion in life," says 37-year-old Ms. Giannini.

A 10-minute drive from her office, the villa's turquoise-tiled indoor pool overlooks a garden with olive groves in the distance. Windows are set to the west and south to catch the best light. "I grew up in the southof Italy, so light is fundamental," says Ms. Giannini, peering out of huge windows at her German shepherd, Gunner, on the patio.

When she and her Web-designer husband Giovanni Battista Guidi bought their villa three years ago, they tore it apart. Ms. Giannini loved the traditional tiled-roof exterior of the house. But the villa felt too old-fashioned and cramped inside: a succession of three dark rooms made up the heart of the living area. With the help of her father, an architect in Rome, Ms. Giannini knocked down the walls, turning the dining and lounge areas into a long, light space with white walls and dark wood floors.

At home as on the runway, historical references guide Ms. Giannini's aesthetic vision. The bright white walls serve as the backdrop to an amalgam of furniture dating from the 1930s to the 1970s. Ms. Giannini picked up a 1950s black bar cabinet at one of her favorite shops on Rome's antique-furniture row, Via dei Coronari. A former equestrian, Ms. Giannini cherishes an antique rocking horse her husband bought for her from a shop in a Dolomite mountain village.

In Ms. Giannini's favorite area, a living room with a marble fireplace, there are stacks of books on 1940s cinema, interior designer Kelly Wearstler, artist Jeff Koons and French photographer Guy Bourdin. Down a short flight of stairs is the "tech room," which holds the designer's collection of 8,000 vinyl records from the 1970s and 1980s, a flat-screen television and a Wii console.

"There is a common aesthetic that accompanies me in my life and my job," says Ms. Giannini. "It's a respect and love for history, reinterpreted in a contemporary way."