Gentry played college basketball at Appalachian State University, where he was a point guard under Press Maravich and Bobby Cremins.

After one year working in private business, he returned to the bench when he received his first full-time collegiate assistant coaching job at Baylor University under Jim Haller in 1980.

After one year at Baylor, Gentry returned to the University of Colorado as an assistant coach from 1981 to 1986 under Tom Apke.

From 1986 to 1989, Gentry served as an assistant at the University of Kansas under Larry Brown, where they won the 1988 NCAA National Championship.

But that assignment was brief, as Gentry accepted the head coaching position for the Los Angeles Clippers weeks after taking the San Antonio job.

Those seasons were marked by the solid play of young players, such as Darius Miles, Elton Brand and Lamar Odom.

Spurs head coach Gregg Popovich remarked "One thing about Phoenix is they are better defensively than in the past.

[6] In July 2013, he returned to the Clippers organization, taking the title of associate head coach, making him Doc Rivers' lead assistant.

On August 15, 2020, after a disappointing performance in the NBA Bubble following the resumption of the 2019–20 season, Gentry was fired as the Pelicans' coach.

[16] Following his dismissal as head coach, Gentry was retained by the Sacramento Kings as the vice president of basketball engagement.