Mostly, though, his office is cluttered with family photos, with his college sweetheart, Barbara, always by his side. One group shot brings together their five children and 22 grandchildren; poignantly, the headshot of a little boy cut into the shape of a heart has been glued on. This is the Nicklauses’ grandson Jake, who drowned nine years ago at 17 months of age. Nicklaus hosts an annual tournament in his honor, The Jake. This year’s raised $2.2 million for the Nicklaus Children’s Health Care Foundation and featured a who’s who of today’s pros. (He has also funded the nearby Miami Children’s Hospital Nicklaus Outpatient Center, and soon a new full-service hospital—for which Nicklaus has pledged to help raise $50 million—will be built in his name.)

Family, philanthropy, the great outdoors—Nicklaus’s passions have all been brought together in this one room. But what gets this 74-year-old living legend into the office nearly every day (often in shorts and boat shoes) is another driving force in his life: a burgeoning business empire. “I have no desire to retire,” says Nicklaus. “I’d retire to this because I enjoy it so much.”

The Nicklaus Cos. is the umbrella corporation for all his business initiatives, though for most of the past four decades golf-course architecture was the primary product. Nicklaus Design has built some 380 courses in 36 countries, 290 of them dreamed up by the patriarch himself. The current fee for one of his Signature designs is upwards of $2 million. While rivals like Arnold Palmer flooded the marketplace with consumer products featuring their imprimaturs, Nicklaus preferred to dig around in the dirt, blending art and science to create his courses. “You can’t believe how many endorsement deals Jack turned down through the years,” says Andy O’Brien, a senior vice president at the Nicklaus Cos. “It usually came back to that he preferred to build courses over everything else.”

But when the economy tanked in 2008 and new golf-course construction suddenly ground to a halt, Nicklaus’s fairway-centered view evolved as well. “I had to think about what else I was going to do to grow the company,” he says. “My objective became to find a way to create a brand that was going to last beyond my lifetime.”

Thus, in the past six years Nicklaus has licensed his likeness to a dizzying number of items. The distinctive Golden Bear logo can now adorn virtually every inch of your person: hats (through a partnership with AHEAD), shirts (Perry Ellis), sunglasses (PeakVision), and shoes (Allen Edmonds). You can start your day drinking Nicklaus water (Aqua Hydrate), have a Golden Bear Lemonade at lunch (Arizona), wash down dinner with a $60 Nicklaus Cabernet (Terlato), and sign your American Express bill—Jack can say “Don’t leave home without it” in Japanese—with a Nicklaus pen (Curtis). All this is made possible because Nicklaus built brand equity not just by winning a record 18 major championships but also by the way he won them: with class and sportsmanship. “Jack Nicklaus is an emblem of the America I admired as a boy in Cuba,” says George Feldenkreis, the chairman and CEO of Perry Ellis, who teamed up with the golfer in 2013 to develop an apparel line. “He’s led an exemplary life. He has achieved great things, but he’s devoted himself to giving back.”

The son of a pharmacist in Columbus, Nicklaus can still recall every inch of the 500-square-foot apartment the family lived in during his boyhood—and Feldenkreis says Nicklaus brings that sensibility to the clothes that carry his name, insisting that they “be affordable to the average American, not just the shopper at Neiman Marcus.” That instinct, as it happens, has turned out to be good business too: In its first year, Perry Ellis’s Golden Bear–embossed line racked up $50 million in sales, a number that’s expected to double next year.

An avid wine collector going back to the 1960s, Nicklaus has allowed himself to go a bit more high-end with the Napa Valley Cabernets and varietals he created with his friend Bill Terlato, CEO of Terlato Wines International. Terlato has been selling about 10,000 cases annually of its four Nicklaus labels since 2010, and it will introduce Jack’s House early next year as a table wine to be priced at $20 a bottle.

It’s a fair bet that the wine deal won’t change Nicklaus’s life from a financial standpoint; his net worth is in the mid-nine figures. So why do it? “Because it’s fun to walk into a restaurant and order your own wine!” he says. (Fittingly, Nicklaus, a connoisseur of butter pecan, is also working on an ice cream deal.)

For all his varied enterprises, however, the one that Nicklaus remains most passionate about is the one that got him started: golf-course design. And business is picking up again. Having opened an office in Hong Kong a quarter-century ago, he was well positioned to become a dominant force in China’s recent national obsession with golf. Nicklaus Design has 26 courses open for play there and 18 more under development.

In keeping with the new business model, a smaller percentage are Signature designs as the patriarch tries harder to sell the company’s services and not just himself. (His son Jackie is the president of Nicklaus Design, and numerous family members work across the enterprises, including a grandson who is a lowly assistant pro at the Bear’s Club in Jupiter.) Nicklaus makes three trips a year to China in his Gulfstream IV-SP, part of a relentlessly grueling schedule. (Not long ago he did eight events in three days across three states, never going to bed before 1 a.m.)

While his empire building shows no sign of slowing, the man himself does occasionally pause to reflect. He has received the Presidential Medal of Freedom and appeared on a five-pound note in the U.K. “All of this because I could hit a golf ball,” he muses. Of course, it’s so much more than that, but Nicklaus still wants to finish the thought. “Isn’t that ridiculous? It’s ridiculous and it’s wonderful.”

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This story is from the September 22, 2014 issue of Fortune.