John Stallworth is in one of his least favorite places, standing in the glow of a spotlight. It’s a late-October day, and he’s behind a lectern in a concert hall in his hometown of Huntsville, Ala., introducing the third annual John Stallworth Legends Round Table. “Regardless of what you think of us when you look at us in the light of our success, we want you to realize your journey is not terribly different from ours,” says Stallworth, who has enlisted a panel consisting of former teammate Franco Harris, ex-Seattle receiver (and ex-congressman) Steve Largent, and Huntsville’s Margaret Hoelzer, a three-time swimming medalist in the 2008 Olympics, to inspire the young athletes and students who fill the audience. Harris and Largent recall the struggles on their paths to Hall of Fame careers. Hoelzer shares her powerful story of being sexually abused as a child.
Stallworth, 62, faced serious challenges of his own. At 8, a viral infection left him temporarily paralyzed on one side. He was a clumsy, pigeon-toed kid who tripped over his own feet—not a person anybody would have pegged as a future NFL star. But this son of a plumber and a maid went on to become a Hall of Fame wide receiver, then developed a multimillion-dollar company in the defense industry, started his own charitable foundation, and became a part-owner of the very team for which he played 14 seasons.
Two mornings after the roundtable, Stallworth sits in the conference room at his family’s offices. He’s still remarkably fit, prompting a comment he often hears: “You look like you could still play.” His stock reply: “I tell myself I have one play left. And I don’t want to go out and prove that’s wrong.”
Stallworth says his terrifying experience with paralysis “brought out a motivation in me to really extend myself.” He didn’t play organized football until his sophomore year of high school. He was rebuffed by the top local high school and then ignored by marquee colleges such as the University of Alabama.
Instead, Stallworth attended Alabama A&M. The Pittsburgh Steelers drafted him in the fourth round in 1974, after a more glamorous wide receiver chosen in the first round: Lynn Swann. Stallworth, says Harris, “was a very unassuming guy who didn’t come in with much fanfare. But you noticed that he steadily kept working hard, pounding away. He just grew into greatness.”
Stallworth was twice the Steelers’ MVP and played in four Super Bowls. He still owns the record for most yards per catch in Super Bowl history. He had two touchdowns in Super Bowl XIV, and his fourth-quarter 75-yard TD catch the following year put the Steelers ahead for good (and landed Stallworth on the cover of Sports Illustrated).
During his NFL days, he was warned about the perils of squandering paychecks. Steelers coach Chuck Noll preached about players’ “life’s work” beyond the sport, saying, “You can’t wait until the day you retire from football and look up and say, ‘What am I going to do now?’” Says Stallworth: “I made up my mind I was not going to play and make a little money and then wonder what happened to it.”
Stallworth returned each off-season to Huntsville, where his wife, Flo, and two children made their home. He “experimented,” he says, earning licenses to sell insurance and real estate and developing apartment complexes while earning his MBA, also from Alabama A&M.
In 1986, the year before his retirement from the NFL, Stallworth, his wife, and engineer Sam Hazelrig established Madison Research, which provided engineering services and technology support for Huntsville’s burgeoning defense industry. They initially worked out of Stallworth’s home, typing proposals on an old electric typewriter on which the “T” was out of whack.
It took a while for people to see Stallworth as a businessman. Athletic renown “was good because it got you in the door,” he says. “In other aspects it was bad because if people couldn’t see you in another role, it was hard for them to do business with you. They had to start to see me as a businessperson. They had to realize that I was competent in this new role.”
Photo By: Walter Iooss Jr./Sports Illustrated
Madison Research earned its first contract with the Anniston Army Depot for two pieces of hardware to test equipment on an M1 tank, then gradually began to blossom. The company eventually managed computer maintenance at the Space and Missile Defense Command’s simulation center. By 2006, when Stallworth sold Madison for $69 million, it had 375 employees in 15 states.
His next unusual turn came in 2009, when Steelers chairman Dan Rooney asked Stallworth to become involved in ownership. He grappled with the dichotomy of field and boardroom. “I know what I felt was important to me and players around the league,” he says. “Would I have to junk all of that now to exist in that [owners’] box?” Says team president Art Rooney II: “It’s great to have him be a sounding board, particularly on things that affect players and retired players.” (For example, Stallworth has expressed his view that extending the regular season to 18 games is “crazy” for the toll it would take on players.)
Along with serving on corporate and charitable boards, Stallworth devotes much of his time to Genesis II, which manages his family’s investments and serves as an umbrella for his philanthropic work. Among other things, his foundation has provided scholarships of more than $350,000 to 125 college students. Says Stallworth: “The money we give to the kids, that changes them. That really excites me.”
Stallworth still gets excited for football too. He was present when the Steelers hosted the Baltimore Ravens in early November, a night when Antonio Brown, whom Stallworth has gotten close to, caught 11 passes. Stallworth was there to help honor a legendary teammate, “Mean” Joe Greene, who was having his number retired. When Stallworth became a part-owner, Greene was working in the Steelers’ front office. Greene looked at him quizzically and said, “Do I have to call you boss now?”
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This story is from the December 1, 2014 issue of Fortune.