The Atlanta Braves selected Malloy in the sixth round of the 2021 Major League Baseball draft.[5] After signing with the team for a bonus of $297,500,[6] he was assigned to the Low-AAugusta GreenJackets.[7] Malloy was assigned to the High-ARome Braves at the beginning of the 2022 season.[8] He slashed .304/.409/.479 with 10 home runs, 16 doubles, and 44 RBIs in 71 games with Rome before being promoted to the Double-AMississippi Braves in July.[9] Malloy appeared in 54 games with Mississippi, hit for a .268 batting average with 11 doubles, six home runs, 31 RBI, .403 OBP, and .824 OPS, and was promoted to the Gwinnett Braves in September.[10] After the 2022 Minor League Baseball season ended, MILB.com considered Malloy an organizational All-Star.[11] He was assigned to the Scottsdale Scorpions of the Arizona Fall League in the 2022 offseason.[12] In the AFL, Malloy primarily played left field, a position he had started playing upon his promotion to Mississippi.[13][14]
Detroit Tigers
On December 7, 2022, Malloy was traded to the Detroit Tigers along with LHP Jake Higginbotham in exchange for Joe Jiménez.[15][16] Malloy was assigned to the Triple-A Toledo Mud Hens to begin the 2023 season.[17] He was selected to play in the All-Star Futures Game at midseason.[18] In 136 games, Malloy batted .277/.417/.474 with 23 home runs and 83 RBI.
On June 3, 2024, Malloy was selected off the 40-man roster and promoted to the major leagues for the first time.[19] Malloy's first major league hit was a 413-foot home run on June 5 against the Texas Rangers. It was the Tigers only hit off Rangers starter José Ureña, and broke up a perfect game in the sixth inning.[20] His third home run on June 30 was an inside-the-park homer off Tyler Anderson of the Los Angeles Angels. It was the Tigers first inside-the-park home run since Victor Reyes in 2021, and the first at Angels Stadium since 2019 (Tommy La Stella).[21] On July 21, Malloy recorded his first career grand slam off Kevin Gausman of the Toronto Blue Jays.[22] On August 19, Malloy was optioned to the Mud Hens after batting .217 with 8 home runs and 20 RBI in 180 at-bats.[23]