The announcement came in an abruptly called video conference around 5 p.m. General manager Al Avila said the retirement was effective immediately.
Bench coach Lloyd McClendon will take over as manager for the rest of the season, which is scheduled to end Sept. 27. Detroit was 21-29 heading into Saturday night’s game and was unlikely to make the postseason.
Gardenhire, who turns 63 next month, was in his third season as Detroit’s manager after he previously had a successful run with the Minnesota Twins. He has had to oversee a significant rebuild with the Tigers that included a 114-loss season in 2019.
Gardenhire said he hasn’t been feeling well and needs to take care of himself. He missed time recently because of stomach issues, and he indicated Saturday that the stress of managing was difficult.
“First off, I’d like to congratulate Gardy for having one of the best managerial careers in baseball history,” Avila said in a statement. “His leadership and hard work over three seasons with our ballclub has helped move us towards our goal of bringing winning baseball back to Detroit. His positive impact on our young players will be felt for years to come.”
The Associated Press contributed to this report.