Jeff Weiner is determined to read the letter, even if he’s running a tad late. For more than an hour the chief executive of LinkedIn has been holding forth on everything from management techniques to employee satisfaction, as well as reflecting on his own career path. These topics are particularly germane to his business, of course, and Weiner gets excited talking about them. His company is all about helping people realize their career goals. Its booming website maintains a permanent, real-time résumé for its users and makes money by matching recruiters with job seekers. But for each minute that Weiner extends the discussion, his packed schedule gets more and more backed up: He’s due to leave later in the day to speak at an advertising conference in Cannes, and at the moment a highly rated engineer who is considering leaving the company waits outside his office to tell the CEO directly why she’s dissatisfied. Weiner is mindful of his time constraints, but he is nevertheless undeterred. The letter must be read. It is, he says, “very meaningful” to him.

Despite maintaining a seemingly paperless office—Weiner’s workspace at LinkedIn’s headquarters in Mountain View, Calif., is immaculate, his desk dominated by twin Apple monitors displaying large, blue LinkedIn logos—he produces from a drawer a three-page, single-spaced memo addressed, simply, to “Dad.” He explains that it is a “mock cover letter” he wrote to his father, a TV executive, 20 years ago. At the time Weiner, now 44, was a management consultant in Boston at a firm called Braxton Associates and was just two years out of the University of Pennsylvania, where he had earned an undergrad degree in economics from the Wharton School. He was unsure of where to take his fledgling career, so his dad encouraged him to write about his aspirations.

The letter is nothing less than an artifact of a young CEO-to-be discussing his as-yet-unrealized destiny. “Dad,” Weiner reads aloud, a hint of a smile on his face, “I enjoy the world of business and the process of problem solving … I don’t just want to make money. I want to add value and feel as though I am making a contribution to the world around me … I get bored quickly … I’d rather be making movies than making the little plastic things that go on the end of your shoelaces.”

These heartfelt declarations are what the Weiner of today would describe as identifying his key values—a prerequisite of leadership, in his mind. After values come mission. And sure enough, as Weiner continues reading from the filial missive, he reaches his younger self ’s personal mission statement: Young Jeff aspires to work in an industry he has dubbed “convergence,” or the coming together of multiple electronic and media industries enabled by new technology. It is 1994, and Weiner wants to join moguls like Ted Turner, Steve Ross, and Rupert Murdoch, who at the time were battling to reshape their domains. (Murdoch, as it happens, still is.) His goal, he explains to his dad, is to get a job in film, TV, or technology, and then after a couple of years he’ll be able to figure out “which path I’d like to follow down the interactive highway.”

Weiner isn’t just showing off by reading out loud his prescient career-planning memo—though it’s safe to observe that precocious young men typically become equally self-assured middle-aged men. The CEO, who favors jeans and a perma-stubble beard, is savvy and self-aware enough to know that his own career trajectory is the embodiment of LinkedIn’s promise to its members: that archiving and articulating your accomplishments is the first step in achieving and managing your goals.

LinkedIn CEO Jeff Weiner Weiner, who favors jeans and a perma-stubble beard, decided at a young age that he wanted to work in media.Photo by Joe Pugliese for Fortune

Indeed, two decades on, Weiner has emerged as a full-blown digital-era management guru—and one who offers a unique blend of charismatic leadership and attention to operational details. His approach involves the use of catchy yet scientifically sound slogans that happen to match up perfectly with the message LinkedIn itself promotes. For example, says Weiner, “values are the first principles we use to make day-to-day decisions.” Then there is the key to his philosophy, the importance of defining “core”—or what a company does so well that it becomes the all-important focus. “For us, ‘connecting talent with opportunity at massive scale’ is our core value proposition,” he says. These bromides roll off Weiner’s tongue. And though many are already accepted business wisdom, his skill at articulating them sets him apart. It also helps that LinkedIn has thrived under Weiner’s leadership. Revenues have soared 20-fold since he joined, in late 2008. And at roughly $20 billion in market value (with just over $2 billion in expected 2014 revenues), the company is one of the stars of the post-financial-crisis crop of Silicon Valley public companies.

Recently Wall Street has fallen a little out of love with LinkedIn: Its stock is off nearly 40% from its peak and has underperformed its peers as investors fret about heavy investments on new products that have yet to pay off. But Weiner appears undaunted. LinkedIn’s efforts in China—where it made its debut earlier this year—and new products aimed at sales professionals should help the company maintain its growth, he believes.

Despite the slumping stock, Weiner remains one of the Valley’s rising stars. He can be seen as a role model to corporate strivers of all ages trying to figure out what they want to be when they grow up. And that makes his profile—what before LinkedIn came around was called a résumé́—worth studying.

Even as a child, Weiner knew where he was going. His mother, Penny, recalls getting lost driving around their suburban Philadelphia neighborhood with young Jeff in the back seat: “He said, ‘Mom, I’m getting bored. We’ve seen the same houses over and over again. I think you need to go this way.’ ” He steered me in the right direction.”

The family moved to suburban Westchester County near New York when Weiner (pronounced “wee-ner”) was in grade school. As a boy Weiner remembers devouring his father’s media-industry trade publications. “He used to come home every night with Variety and Hollywood Reporter,” Weiner says. “I’d be looking at the box office grosses and the television ratings. I grew up with media in my blood.”

After a short stint at Braxton, Weiner was able to scratch his convergence itch by landing a corporate development job in Los Angeles with filmmaker Warner Bros. A voracious reader, he’d gotten hooked on Nicholas Negroponte’s book Being Digital, which described a future of technologies that would disrupt traditional media. Weiner volunteered to write the business plan for what became Warner Bros. Online, and in the process he caught the eye of Warner co-CEO Terry Semel.

Semel would play a defining role in Weiner’s career. When Semel left Warner and formed his own investment firm, Windsor Media, Weiner followed in 2000, at the height of the Internet bubble. Barely a year later, after the bubble had popped, a badly ailing Yahoo hired Semel as its CEO, and once again Semel brought Weiner with him, installing his young protégé in Yahoo’s dealmaking department along with Toby Coppel, another young executive from Windsor.

LinkedIn's Jeff Weiner with Terry Semel Weiner walks and talks with his business mentor Terry Semel, the former Yahoo CEO, at the Allen & Co. conference in Sun Valley, Idaho, in 2010.Photo by Matthew Staver—Bloobmerg/Getty Images

The duo identified search advertising, Google’s domain, as Yahoo’s weakness and set out to acquire companies to catch up. “Jeff led that effort, first from corporate development and then operationally,” says Coppel. Yahoo bought search engine Inktomi and search ad platform Overture, which owned AltaVista, a search pioneer. Weiner later moved into his first managerial role by heading up some of the newly acquired businesses. Along with his leadership role came one of his first business slogans—FUSE, which stands for “find, use, share, and expand.”

Weiner’s FUSE approach for search was visionary: Developing products that allowed users to share information predated Facebook and Twitter. The strategy also helped solidify his reputation as a leader who articulated his wishes clearly. “It was an example of his ability to develop conceptual frameworks and render them in understandable formats,” says Tim Cadogan, who worked for Weiner at Yahoo. Weiner was also known during his Yahoo days for wielding his fierce intelligence as something of a blunt instrument. “He could be a little harsh,” recalls Cadogan. “He was famously intimidating, asking an onslaught of questions.”

Jeff Weiner at Yahoo in 2005Weiner in 2005, when he was the vice president in charge of Yahoo’s “search and marketplace” business unit.Photo by Peter DaSilva—The New York Times/Redux

The strategy may have been coherent, but it didn’t work. Looking back, Weiner calls Yahoo’s strategic approach a “challenging situation because the very core that helped the company become so successful, which was organizing the consumer web, became a real vulnerability.” And so rather than investing more heavily in media properties, whose advertising sales had been crushed in the dotcom implosion, Yahoo attacked Google in search advertising. But Google thrashed Yahoo at that game. And in 2008, while on paternity leave after the birth of the first of his two daughters, Weiner decided to quit his job at Yahoo. He was already working on a new plan.

Even before joining LinkedIn, Weiner used his professional network masterfully in plotting his next move. It is common for Silicon Valley executives who are between jobs to park themselves at a venture capital firm as an “executive in residence.” Their job is to help the firm scout investments, ideally where the executive could end up in management. Andrew Braccia, who had worked for Weiner at Yahoo, had joined Accel Partners, and he helped Weiner land a position there. As it happened, James Slavet, another former Weiner employee now at VC firm Greylock, also offered Weiner an EIR gig. It was an unconventional move to accept identical positions at competing firms, but that’s just what Weiner did.

The dual-VC role didn’t last long. LinkedIn founder Reid Hoffman—whom Weiner had met at a dinner hosted by Fortune—was searching for a new CEO for the company. In LinkedIn’s earliest days, Hoffman himself had been the CEO, but he decided he was more suited to being chairman, given that he’s more of a thinker and builder than an operator. (Through dual-class voting shares, Hoffman controls LinkedIn to this day.) He hired Weiner as interim president at the end of 2008 and promoted him six months later. “He really focuses on a culture of leadership, especially how to ask people to step up as leaders,” says Hoffman of Weiner.

The Hoffman-Weiner relationship has emerged as one of the happiest founder-CEO partnerships in Silicon Valley. Weiner keeps a photo in his office of himself and his boss at an Allen & Co. media conference in Sun Valley, Idaho, both grinning widely. Hoffman’s office is next door, though he spends one day a week at Greylock, the venture firm he joined, coincidentally, after Weiner. He refers to Weiner as a “late-stage founder” who “embodies the mission.”

LinkedIn's Jeff Weiner and Reid Hoffman Weiner keeps this photo of himself with LinkedIn chairman Reid Hoffman in Sun Valley, Idaho, on the desk in his office.Photograph courtesy of Allen & Company

While LinkedIn’s products serving recruiters, marketers, and regular people in their careers predate Weiner’s arrival, its publishing platform is one of his key initiatives. (LinkedIn’s three revenue generators are software for recruiters; advertising and marketing sales primarily to employers; and premium subscriptions to users.) For example, LinkedIn created an Influencer program in 2012 that anointed 100 or so key industry figures (including the author of this article) and empowered them to publish their career advice on LinkedIn. A key Influencer is Weiner himself, who has written 28 posts, mostly on management topics, and is “followed” by 1.4 million people. He has offered thoughts, for example, on the right way for a leader to give feedback (clearly differentiate between suggestions and orders), on retaining talent (by providing mentorship, career path guidance, and recognition), and on the importance of removing people who are wrong for their jobs (including a well-liked veteran who isn’t performing).

Weiner has adopted the language of compassion, invoking its importance at seemingly every turn. He also recognizes that compassion wasn’t always his strong suit, especially at Yahoo. “I made the same mistake a lot of less experienced, more junior executives make of seeing the world through your own perspective and projecting onto people the way they do things,” he says. Empathy, or feeling someone’s pain, can hinder a leader from being helpful, Weiner says. But compassion—the ability to understand another person’s pain—enables you to “do something about the way that person is feeling. Compassion has essentially become my first principle of management.”

Compassion, leadership, values, and vision are all good and fine, of course, provided they succeed. Given that Weiner has been CEO for more than four years, so far so good. Heath Terry, an analyst at Goldman Sachs, projects that LinkedIn’s 2014 revenues will be $2.2 billion, a 41% year-over-year growth rate. What’s more, the company’s revenue stream is well diversified. Software for recruiters still provides the biggest chunk of business—58% of sales—but advertising and premium-subscription revenues are significant as well. Says Terry: “What LinkedIn is about is this incredible layer of data for white-collar professionals.” LinkedIn’s stock was recently off a whopping $100 from its high last September. The Goldman analyst ascribes the drop primarily to compressed valuations for many high-growth Internet stocks. He also says some investors have soured on LinkedIn’s high costs from investing in new businesses. And after a big pop in the stock post-IPO, some investors may well have wanted to take profits.

Linkedin CEO Jeff Weiner with Reid Hoffman Weiner and chairman Reid Hoffman at the New York Stock Exchange for LinkedIns IPO in May 2011.Photo by Stan Honda—AFP/Getty Images

To keep the company growing, Weiner has his eye on a relatively untapped category of workers: salespeople. Its new “sales navigator” product allows users to tap into LinkedIn’s database with tools to aid their selling abilities. Non-U.S. markets, notably China, also represent a big opportunity. Upwards of 70% of LinkedIn’s traffic comes from outside the U.S., compared with 30% of its revenues. LinkedIn opened for business in China this February, and the market is so important to the company that Hoffman has traveled to China to work with the regional president. As well, LinkedIn is increasingly marrying its big-data analytical ability with its emerging presence as an online publisher. In addition to its high-profile contributor network, the company recently allowed all users to post longer-form essays on their profile pages. Through acquisitions like Pulse and, just recently, Newsle, LinkedIn has also gotten good at sending users relevant information by email—all designed to increase the time users spend on LinkedIn.

The CEO is a natural evangelist for LinkedIn’s publishing platform. He says he’ll frequently meet with customers who share successes in recruiting, and he’ll urge them to publish their accounts on LinkedIn. “I’ll say, ‘That’s a post! You’ve got to write that. That’s how you build your company’s talent brand.’ ”

 
Weiner’s own brand as a CEO is extremely valuable right now, and so is his net worth. He may not be a founder, but LinkedIn has rewarded him generously. His stock awards amount to over $250 million at current prices. Yet for all his success, Weiner hasn’t really been tested yet, at least not by the sorts of calamities that typically hit high-growth technology companies—a missed product cycle, a recession, unexpected competition, a slowing growth rate. (One test certainly would be investors continuing to dump LinkedIn’s shares.)

Hoffman predicts Weiner will be LinkedIn’s CEO five years from now, though it’s worth noting that Weiner’s immediate predecessor resigned after Hoffman concluded that his skills didn’t match the company’s needs. For his part, Weiner has multiple outside interests, as well as a young family, that keep him energized. He’s on the board of financial-software maker Intuit, for example, and is active with philanthropies including the education-focused DonorsChoose and Malaria No More. He’s also a passionate foe of processed sugar, and he recently invested in a California maker of no-sugar-added energy bars called Frontier Bites.

If he hadn’t gone into the media business, says Weiner, he might have made a career in education. He never was a fan of rote learning, and he remains interested in education reform. Having chosen the corporate life over teaching, however, he’s starting to think of LinkedIn as an important part of the job-training puzzle. “I didn’t realize until I got to LinkedIn that without access to economic opportunity, nothing else matters,” he says. In Weiner’s view, LinkedIn provides that access. It’s enough to make a man want to write another memo.

LIN.08.11.14.Jeff.Weiner.05B

This story is from the August 11, 2014 issue of Fortune.