He was 62.
A team spokeswoman confirmed DeBusschere died of a "massive heart attack."
Playing for Knicks teams which featured five Hall of Famers, DeBusschere was one of the league's elite power forwards, making the All-Defensive Team six times.
One of his well-known teammates was former U.S. Sen. Bill Bradley.
"Dave DeBusschere was a loyal friend, an unselfish teammate, and a quality human being," Bradley said in a statement. "His strength, dedication, and modesty lay at the core of our great Knick teams. He was like a brother to me. The world seems like a diminished place today for me, for his family, for hundreds of his friends and thousands of his fans."
Nicknamed "Big D" for his stellar defensive play, DeBusschere played with fellow Hall of Famers Willis Reed, Bill Bradley, Walt Frazier, and Earl Monroe with the Knicks.
His chief role was to grab rebounds and shut down the opposing team's best forward. Since he previously served as player-coach of the Pistons, DeBusschere was willing to sacrifice his individual achievements for team goals, a hallmark of those Knicks teams.
"I am deeply saddened by the news of Dave's passing," Willis Reed said in a statement. "He had a profound impact on the landscape of professional basketball, both as a player and an executive."
Also in a statement, the DeBusschere family said, "On behalf of the entire DeBusschere family, this is a devastating loss for our family. Dave was a wonderful father, husband, and friend that we know will be missed by not only the entire DeBusschere family, but all New Yorkers that enjoyed watching him. We hope he will be remembered for the all the great moments he gave us on and off the court."
DeBusschere, whose No. 22 is retired by the Knicks organization, also played major league baseball with the Chicago White Sox in 1962 and '63 while playing with the Detroit Pistons in the NBA. He was a player-coach with the Pistons from November 1964-to-March 1967 before being traded to the Knicks.
"There's not one other guy in this league who gives the 100 percent DeBusschere does, every night, every game of the season, at both ends of the court," Bill Bridges of the Atlanta Hawks once told New York Newsday.
DeBusschere, who starred collegietely at the University of Detroit, also served as commissioner of the American Basketball Association, and was the Knicks' general manager from May 1982-to-January 1986, and later was the team's Executive Vice President and Director of Basketball Operations.
He also served as Vice President and General Manager of the American Basketball Association's New York Nets. The following year, he was hired as Commissioner of the ABA, and helped the league merge with the NBA after the 1975-76 season.
Patrick Ewing likely was his most celebrated draft pick. The Knicks got Ewing in the 1985 lottery.
In his 12-year career, DeBusschere played in 875 games, averaging 16.1 points and 11.0 rebounds per contest. He was elected to the Naismith Memorial Basketball Hall of Fame in 1983, and was named to the NBA 50th Anniversary All-Time Team in 1996.
Memphis Grizzlies President Jerry West, who competed against DeBusschere as a player, and dealt with him as an executive, also was emotionally affected by the news.
"This is a very sad day for me personally," West said in a statement. "Not only did his family and the NBA lose a great representative of what is best about the NBA, we also lost one of the real classy people that has been involved with the sport of basketball."
Another tribute came from NBA Commissioner David Stern.
"As a player, coach, general manager, and ABA Commissioner, Dave DeBusschere was a winner," Stern said. "He was a hard-nosed, blue-collar hero who gave all of his considerable energy to our game. I have been privileged to know Dave in all facets of his NBA and post-NBA life. Our game has lost an icon, and the world has lost a good man. I extend the heartfelt condolences of the NBA family to his wife Geri and Dave's entire family."
"He was the final piece of the puzzle," said guard Walt Frazier. "Dave was a blue-collar type of player who led by example with his tenacity on the court. I will always remember him sitting in the corner of the locker room after the game, spent, because he always had given it all he had. Because of that, the players respected him immensely."
The Knicks and Los Angeles Lakers met three times in four years in the NBA Finals, with the Knicks winning two of the showdowns in 1970 and '73. In the deciding Game Seven in 1970, he had 18 points and 17 rebounds.
"I'm very sorry to hear that Dave passed away," Ewing said. "He's the man who brought me to New York. I've always had nothing but the utmost respect for him."