Colangelo graduated from the University of Illinois, where he was a member of Phi Kappa Psi Fraternity.

Colangelo arrived in Arizona newly hired as the first general manager of the expansion Phoenix Suns. There, he made it clear from the start that his desire was to win an NBA championship.

Colangelo lost a flip of the coin in 1969 to draft Kareem Abdul-Jabbar. But the Suns remained competitive most of the 1970s, and they almost made Colangelo's dream come true when they reached the Finals in 1976, losing to the Boston Celtics in six games. Colangelo had two stints as head coach during that decade, compiling a record of 59 wins and 60 losses as coach.

During a good portion of the 1980s, Colangelo's Suns faced trouble, as some of them were involved in an infamous drug scandal, and the Suns flirted with mediocrity. But when Colangelo purchased the team outright in the wake of the scandal, and subsequently made a trade for Kevin Johnson in 1987, that picture began to change.

The Suns started making the playoffs, something they would do for 13 straight years, and in 1989, Colangelo was an essential part of the group that planned to build America West Arena, providing financial backing. In 1992, Colangelo traded Jeff Hornacek to the Philadelphia 76ers for Charles Barkley. The trade proved to be productive for the Suns, and they reached the NBA Finals for the second time in 1993, this time losing to the Bulls in six games. Barkley's relationship with Colangelo, however, grew sour over the years, and in 1996, he was traded to the Houston Rockets.

Before that, in 1995, Colangelo had been granted a Major League Baseball expansion team: The Arizona Diamondbacks. The Diamondbacks' began to play in 1998, one year after another Colangelo team, the Women's National Basketball Association's Phoenix Mercury, also started. The Mercury reached the WNBA finals, losing to the Houston Comets. Another Colangelo team, Arena Football League's Arizona Rattlers, gave Colangelo his first championship in 1994, and once again in 1997. The Rattlers have been playing since 1992. Colangelo was also instrumental in bringing the National Hockey League's Winnipeg Jets to Phoenix in 1997. The Coyotes now play in the suburb of Glendale as the Phoenix Coyotes.

With the help of such notables as Mark Grace, Tony Womack, Luis Gonzalez, Curt Schilling and Randy Johnson, the Diamondbacks were finally able to give Colangelo what he wanted most: A World Series title. They beat the New York Yankees in seven thrilling games in 2001 to win the World Series. The series ended on a walkoff single by Luis Gonzalez in the 9th inning of Game Seven against the usually unhittable Mariano Rivera.

Colangelo, who is good friends with boxing promoter Bob Arum, has also tried to bring boxing to Arizona, and was one of the persons behind the building of the Dodge Theatre there. The Dodge Theatre is currently an important boxing and performing arts venue in the American Southwest.

He has received several community awards, and recently, he turned over the Suns' presidency to his son Bryan. His relationship with Barkley has improved with years, and Colangelo has declared himself a newborn Christian, reason that he credits for his change of heart about Barkley.

Colangelo has also been known for his no-nonsense ownership style. Players like the Suns' Dennis Johnson and Jason Kidd and the Diamondbacks' Bobby Chounard have been traded or released from his teams after their personal problems came to the public light.

Colangelo has been named the NBA's Executive of the Year four times.

On April 4, 2004, Colangelo was elected into the Naismith Basketball Hall of Fame. Later that month, Colangelo sold the Phoenix Suns to an investment group headed by Robert Sarver for $401 million dollars.

Late in the 2004 baseball season, Colangelo sold his controlling interest in the Arizona Diamondbacks team to a group of investors lead by Jeff Moorad [1].

In December of that year, Colangelo was diagnosed with prostate cancer.

In the Summer of 2005, Colangelo was named the sole director of USA Basketball.