"Helping guide this organization has been the thrill of a lifetime, and having worked side-by-side with him since he’s been here, I know we couldn’t be in better hands than with Brad guiding the team going forward," Ainge said in a statement. "I’m grateful to ownership, all of my Celtics colleagues, and the best fans in basketball for being part of the journey."
Stevens has been head coach for the last eight seasons.
"I’m grateful to ownership and to Danny for trusting me with this opportunity," Stevens said. "I’m excited to tackle this new role, starting with a wide ranging and comprehensive search for our next head coach. I love the Celtics, and know the great honor and responsibility that comes with this job. I will give it everything I have to help us be in position to consistently compete for championships."
The Celtics said "Ainge will continue to work with the team on transition planning through the upcoming off-season."
A search for a new head coach will begin immediately.
(Photo: Getty Images)