Baseball America wrote that he has a "physical frame and produces above-average bat speed (that) combined with the natural leverage in his swing, translates into plus raw power".

Stewart started the 2016 season with the Lakeland Flying Tigers and was later promoted to the Erie SeaWolves;[8] he posted a combined .255 batting average with 30 home runs and 87 RBIs between both teams.

[9] His homer total tied him for fifth among all Minor Leaguers in all organizations, while his 24 home runs, .534 slugging percentage and .924 OPS in 104 games at Lakeland led the Florida State League.

[10] Stewart returned to Erie in 2017 and spent the whole season there, compiling a .256 batting average with 28 home runs and 86 RBIs in 136 games.

[18] On September 20, Stewart hit his first two major league home runs in his first two at-bats against the Kansas City Royals and had six RBI in the game.

Stewart won the starting left field job for the 2019 Tigers, and hit a game-winning home run on opening day, March 28, against the Toronto Blue Jays.

[20] He hit his first career grand slam on April 6 against the Kansas City Royals, which also proved to be the game winner in the Tigers 7–4 victory.

[27] He played in 103 games for the Triple–A Worcester Red Sox, hitting .237/.364/.450 with 19 home runs, 55 RBI, and 9 stolen bases.