The NBA announced Saturday that Conley joins Grant Hill (3) and Jason Kidd (2) as multiple winners since the award's inception in the 1996. The point guard also won in 2014.
"He's very deserving as just a wonderful human being, a class act on the court, the way he carries himself and certainly all the things he does in the community," Grizzlies coach Dave Joerger said. "He plays the game the right way, and then he carries that over into the community and all the positive things he's done here in the last nine years is just fantastic."
The NBA will make a $10,000 donation on behalf of Conley to his charity of choice, Methodist Healthcare Foundation. The money is earmarked for the sickle cell center.
Conley received 58 of 327 first-place votes and 2,209 total points from NBA players, who voted among finalists Kyle Korver (Atlanta), Pau Gasol (Chicago), Damian Lillard (Portland), Shaun Livingston (Golden State) and Luis Scola (Toronto).
The annual award for ethical behavior and fair play is named for former Detroit Pistons guard and Hall of Famer Joe Dumars.
Conley has not played since March 6 with Achilles tendinitis in his left foot. Conley started all 56 games he played this season, averaging 15.3 points, 2.9 rebounds and a team-high 6.1 assists.
He also led all qualifying NBA players with an assist-to-turnover ratio of 4.07.