Jackson finished ahead of the Milwaukee Bucks' Brook Lopez and the Cleveland Cavaliers' Evan Mobley, garnering 56 out of 100 first-place votes and 391 total points. Lopez came in second with 31 first-place votes and 309 points, while Mobley came in third with eight first-place votes and 101 points. The voting panel consisted of 100 sportswriters and broadcasters.
Jackson joins Alvin Robertson, Kawhi Leonard and Dwight Howard as the only 23-year-olds to win the award. Only Howard, by a matter of a few months, was younger than Jackson when he received the honor.
Jackson led the league in blocked shots (3.0 per game) for the second consecutive season while anchoring the NBA's third-ranked defense (110.7 points per 100 possessions).
The Grizzlies allowed only 106.6 points per 100 possessions with Jackson on the floor and opponents shot only 44.0% in the paint when he was the closest defender, which ranked as the stingiest in the league among rotation players.
"Team defense really helps us. It goes a long way," Jackson said on the TNT broadcast that announced the award winner.
Jackson joined an exclusive group of players that has averaged at least three blocks and one steal per game for a top-five defense in the four decades that the Defensive Player of the Year Award has existed. The only three other players who have done so are Hall of Famers Hakeem Olajuwon, David Robinson and Ben Wallace, who combined to win four DPOY awards.
Jackson was seen reacting to winning the award with his family in a video posted to social media, calling it a "surreal feeling" in a second video posted by the Grizzlies.
Jackson is the second player in Grizzlies franchise history to win the honor, following center Marc Gasol (2012-13).
Jackson also earns the award's first Hakeem Olajuwon Trophy, which the NBA introduced before the season as part of a leaguewide rebrand of the end-of-season honors.
The Associated Press contributed to this story.