LeMahieu went 4 for 5 with two runs scored and an RBI in the 6-3 victory Wednesday in New York City. The Yankees also got home runs from Gary Sanchez and Clint Frazier.
The win gave New York a two-game sweep over Atlanta.
"He's a special hitter," Yankees manager Aaron Boone said of LeMahieu. "He's a guy that uses the whole field, has pop, handles righties and lefties.
"He has tremendous bat-to-ball skills and does a great job of just laying the bat head in the zone for a really long time."
The Braves took an early lead on a two-run homer from Johan Camargo in the top of the second inning. Sanchez and Frazier then hit back-to-back solo home runs in the bottom of the second inning to tie the score at 2-2.
The Yankees added two more runs to take the lead in the bottom of the fourth inning before they added insurance in the bottom of the fifth frame. LeMahieu made the score 5-2 with an RBI single for the first score of the inning. Luke Voit then plated LeMahieu with another RBI single to give the Yankees a 6-2 edge.
Braves catcher Travis d'Arnaud brought in the final run of the game with an RBI single in the top of the ninth inning.
Masahiro Tanaka allowed five hits and two runs in four innings for the Yankees, but was not on the record for a decision. Braves starter Huascar Ynoa allowed four hits and two runs in one inning.
Frazier went 3 for 4 with two runs scored and an RBI in the win. Voit went 2 for 5 with an RBI for the Yankees.
Shortstop Dansby Swanson went 3 for 5 for the Braves. Nick Markakis and Camargo each collected two hits in the loss.