During his 18-year career as general manager for the Boston Celtics, Ainge was known for making bold moves to help the team rebuild, and clearing cap space.

While in college, Ainge also played parts of three seasons with the Toronto Blue Jays of Major League Baseball (MLB), mostly as a second baseman.

He went on to coach the Suns for three seasons before joining management of the Celtics, with whom Ainge has three NBA championships to his credit (two as a player, one as a team executive).

He led the Highlanders' basketball team to consecutive AAA state titles in 1976 and 1977,[2][3] earning all-state honors both years, and was considered one of the top football recruits in Oregon at wide receiver.

He hit one of the best-known shots in the 1981 NCAA tournament, against Notre Dame in Atlanta in the Sweet Sixteen, when his coast-to-coast drive and lay-up with two seconds remaining gave the Cougars a one-point win.

Ainge is one of 13 athletes who have played in the National Basketball Association and Major League Baseball, along with Frank Baumholtz, Hank Biasatti, Gene Conley, Chuck Connors, Dave DeBusschere, Dick Groat, Steve Hamilton, Mark Hendrickson, Cotton Nash, Ron Reed, Dick Ricketts, and Howie Schultz.

Celtics head coach Bill Fitch gave Ainge a rough time, saying his batting average was better than his shooting percentage on the basketball court.

Ainge played sparingly during his rookie season (1981–82), but broke into the starting lineup in his second year, averaging 9.9 points per game.

Ainge remained an important role player off the bench, helping the Celtics defeat the rival Los Angeles Lakers in the NBA Finals that year.

The Celtics traded Henderson to Seattle in the off-season, returning Ainge to the starting guard position opposite Dennis Johnson.

In 1989, Ainge was traded to the Sacramento Kings, along with Brad Lohaus, for young center Joe Kleine (whom the Celtics saw as a possible successor to the aging Robert Parish) and Ed Pinckney.

He scored 45 points for the Kings in a loss to the Golden State Warriors, matching a career high that he had set just a few months prior against the Philadelphia 76ers while still playing for the Celtics at that time.

He had stated in media interviews that he ideally wanted to stay in Portland and would contact Blazers management before seriously entertaining offers from other teams.

At the time of his retirement, he had the highest personal winning percentage in NBA history among players with at least 1,000 career games, edging out Kareem Abdul-Jabbar 69.0% to 68.8%.

In a 1994 postseason game, Ainge rifled an inbounding pass at the head of Houston Rockets guard Mario Elie, striking him in the face and snapping his neck back.

This incident eventually forced the Suns to trade Horry to the Los Angeles Lakers for Ainge's old teammate Cedric Ceballos.

However, Ainge kept the support of both the Celtics' ownership group and—perhaps most importantly—legendary former head coach Red Auerbach, who was employed by the team as a "senior assistant" until his death in October 2006.

[18] On May 3, 2010, Ainge was fined $25,000 for tossing a towel to distract then Cleveland Cavaliers forward JJ Hickson shooting a free throw during Game 2 of the Eastern Conference Semifinals.

[23] Eight days later, the deal also included a 2020 second round pick from the Miami Heat as compensation relating to a prior injury to Thomas.

On June 2, 2021, Ainge announced his retirement and named head coach Brad Stevens as his replacement as President of Basketball Operations.

In return, the Jazz received Russell Westbrook (who later bought out the contract to sign with the Clippers), Juan Toscano-Anderson, Damian Jones and a 2027 first round pick.

While only a brief appearance, Ainge was dubbed "The Bad Shot Guy" after catching and shooting the ball at the same time while Charles Barkley roamed the court after having his skills stolen by the Monstars.

Ainge and his wife, Michelle, reside in Wellesley, Massachusetts; they have six children, one of whom, Austin, is director of player personnel for the Boston Celtics[29] and like his father, played basketball at BYU.