The honor recognizes players deemed the best teammate based on unselfish play, leadership on and off the court as a mentor and role model to other NBA players, and commitment and dedication to the team.
Nearly 300 NBA players voted for this past season's recipient through confidential balloting conducted by the league office. Nominees included six players from each conference nominated by a panel of NBA legends.
Duncan received 72 first-place votes and totaled 1,494 points. The Memphis Grizzlies' Vince Carter finished second in voting (818 points, 28 first-place votes), followed by the Atlanta Hawks' Elton Brand (707, 21).
"That's what makes it the most special, knowing that people voted me and chose me for this award," Duncan said. "An amazing honor. It's taken so long to get to this point, to accept the award. But I was really stoked when I heard about it. It's truly an honor."
Duncan has played a key role in leading San Antonio to five NBA championships as well as postseason berths in each of his 18 seasons in the league. He was named to his 15th NBA All-Star team last season, 15th all-NBA team and 15th all-defensive team.
Duncan's latest award is named after Jack Twyman and Maurice Stokes, former teammates on the Rochester/Cincinnati Royals from 1955 to '58.
Stokes suffered an injury in the last game of the 1957-58 regular season. He ultimately fell into a coma and was left permanently paralyzed. Doctors diagnosed Stokes with post-traumatic encephalopathy, a brain injury.
Twyman supported Stokes the rest of his life, becoming his legal guardian and advocate. Twyman played a role in organizing the league's Maurice Stokes memorial basketball game, which raised funds for the latter's medical care, and after Stokes' death in 1970, for other players in need.
Stokes was enshrined in the Naismith Memorial Hall of Fame in 2004 after years of lobbying by Twyman, who was elected to the Hall in 1983.
"I've done my research. I have," Duncan said of the story behind the award. "I've spoken to a number of different coaches, and [Spurs coach Gregg Popovich] was great at kind of giving me the background and the history of the teammates and what the award truly means. That makes it even more special."
The NBA, as part of its support for the award, will make a $25,000 donation split among five charities selected by Duncan: My Brother's Workshop, American Cancer Society, Ten Thousand Helpers, St. Croix Interscholastic Athletic Association and St. Croix Foundation.
Duncan will be officially presented the award at a Spurs home game this fall by Shane Battier, who won the award in 2013-14.