Michael Bruno keeps chic apartments on the Left Bank in Paris and in the West Village in Manhattan, but he considers Sunset Hill—his beloved 1920s farmhouse in Sagaponack, N.Y.—his real home.

Perched upon the highest point in this Hamptons hamlet, the nine-room shingle-style house peeks through a verdant tapestry of century-old oak, maple, birch and elm trees like a king surveying his kingdom. While Sunset Hill encompasses only seven acres of the original estate’s 500, the property maintains a grand feel: Two enormous turn-of-the-century barns reside on-site, as well as a charming cottage that doubles as a guesthouse, a grove of fragrant crab apple trees, an abundance of blue-purple hydrangeas and a field of colorful wildflowers.

“The house was built by one of the original landowners of the Hamptons and was used as a second home,” the 41-year-old entrepreneur says. “When I bought it, it hadn’t been touched for 50 years.”

Bruno spent two years renovating the 3,400-square-foot carriage house. Today, its interior resembles an art gallery of white walls and ebonized oak floors—providing the perfect background for the 19th- and early 20th-century pieces Bruno has collected from around the world. “I chose the color palette of black and white because my previous house was full of color, and most furniture collectors like myself want the furniture to stand out on its own,” he says. “I found all of the pieces—everything from the French bistro mirror in the kitchen to a set of 1950s mahogany armchairs by Jean Michel Frank—online.” Assembling the home’s decorative items and furniture was, in essence, a trial run for his latest venture, www.1stdibs.com—an online design source for high-style American and European furnishings and decorative accessories.

With its zebra-skin ottomans and rugs, summery bamboo floor mats and eclectic mix of antiques, limited-edition new pieces and fine art, Sunset Hill is, by design, at once fashionably casual and comfortable. It is the perfect pit stop, Bruno says, for his travels between Paris and New York. It was the tranquillity of Sunset Hill and the seclusion of Sagaponack that appealed most to the businessman, whose work requires constant travel. “I was living in San Francisco, and I came here once and said, ‘This is for me.’ Of all the Hamptons towns, Sagaponack has the most rural flavor,” he says.

Indeed, when Bruno steps outside his front door, the surrounding environs are so casual in nature that he thinks nothing of being barefoot. He can admire the rows of corn growing next door, tractors grooming the fields of green across the street and white-tailed bunnies bouncing across the yard. On a summer morning, Bruno and Sampson, his Saint Bernard, walk to the beach, where Bruno trains for Sag Harbor’s annual triathlon—swimming in time to Sampson’s cheerleader-like barking. “I like being near the water,” Bruno says. “Being near it is key to me, and just knowing that it’s there relaxes me.”

When they’re not beach-bound, the twosome often stroll to Pike’s Produce Market to pick up some homegrown vegetables, or they venture out to Sagaponack’s old-fashioned main street, stopping at the post office and the general store, where they occasionally bump into resident artists and writers such as Ross Bleckner and Kurt Vonnegut. “Unlike other Hamptons towns, there are no fences and no private hedges,” Bruno says. “The land is open, and you can walk across the yards.”

In autumn, he eagerly awaits the turning of the leaves, and in winter he anticipates Sagaponack’s snowfall, where there is nary a tire tread or human footprint to mar its silvery beauty. But it is Bruno’s vast yard, which requires an army of gardeners a half day just to mow it, that gives him the most pleasure. “I spend weeks at a time at Sunset Hill,” he says, adding that he has learned to enjoy puttering in the yard, weeding here and planting there. The yard is also ideal for entertaining, whether it is an alfresco dinner for four guests or 40.

Larger dinner parties take place on the backyard’s terrace, floored with reclaimed slate from Bridgehampton’s St. James Hotel, or in the barns, one of which has been converted into a great room encircled with a gravel courtyard. “I love to set the table,” he says, “and I usually invite a friend who can cook.” Last summer, for instance, a gourmet friend arrived armed with a 17th-century cookbook. Together, Bruno and his guest orchestrated a series of elaborate parties around the book’s menus.

Hunting for the perfect place on the property to host each unique gathering is as much fun as creating the guest list. “I like to find a different spot for each dinner,” Bruno says. “I look for a different bush in bloom. It completely varies with my mood.”

Although every room of the house affords spectacular views, Bruno designed the kitchen as a bridge between his beautiful interiors and the great outdoors. A brass-framed mirror, strategically positioned above the stove, allows Bruno to enjoy the gardens while he cooks. A special find in the kitchen is the dining table, culled from a Paris flea market and cut down to fit the space.

When the last course is finished and the last guest bids adieu, Sunset Hill is still very much alive. “At night, when you open the French windows in the bedroom, you can hear the ocean crashing,” Bruno says. “Between the sea and the breeze in the trees, it’s like being in an old-fashioned sleeping porch.”