[1] His versatility on defense and hitting ability earned LeMahieu the nickname "LeMachine" from Yankees teammate Gary Sánchez.

[3] With the Yankees, he was named a starter on the 2019 All-Star team, and won his first career Silver Slugger Award that year.

In the post-season, he was selected to the All-Tournament team for the Baton Rouge regional after hitting .300 and scoring seven runs.

[citation needed] LeMahieu finished the season leading the team in batting average, .350 and total hits, 96.

In Game 1 of the Championship Series, LeMahieu hit a home run in the seventh inning giving LSU the lead temporarily.

Down to their final out in the ninth inning, LeMahieu hit a game tying double off the left field wall.

He then led off the 11th inning with a walk, stole second base with two outs, and scored the game's winning run.

On May 30, 2011, the Cubs promoted LeMahieu to the major leagues when Jeff Baker was placed on the 15-day disabled list with a left groin strain.

[16] That day, LeMahieu made his major league debut pinch-hitting for the pitcher John Grabow, grounding into a double play.

[18] On December 8, 2011, the Cubs traded LeMahieu and Tyler Colvin to the Colorado Rockies for Casey Weathers and Ian Stewart.

On May 23, 2012, LeMahieu was called up to the major leagues to replace injured Jonathan Herrera as a utility infielder.

He returned to Colorado Springs when Herrera was activated,[20] and was recalled to the Rockies on July 17 when Chris Nelson was hospitalized.

He won his first Gold Glove[23] with 16 Defensive Runs Saved[24] and led the majors with 99 double plays.

[citation needed] In the two-game London Series (which marked the halfway mark of the Yankees season) at the end of June, LeMahieu had seven hits in 12 at bats, three doubles and seven runs batted in, helping the Yankees to sweep the Red Sox in the series.

[40][41] This won LeMahieu his first career Player of the Week award, which he followed up by winning the June AL Player of the Month Award for the first time (batting .395/.434/.658 with six home runs, 29 RBIs, 26 runs scored, and 45 hits) and being elected as the starting second baseman for the All-Star game.

In Game 6 of the 2019 ALCS, LeMahieu hit a game-tying two-run home-run in the ninth inning to tie the ballgame at 4–4, with the Yankees two outs from elimination.

[48] However, he suffered a left thumb sprain against the Boston Red Sox on August 16 and was placed on the 10-day injured list.

[51] However, LeMahieu became the first player in MLB's "modern era" to win a batting title in both the American and National Leagues.

[4] With teammate Luke Voit leading MLB with home runs (with 22), the duo became the first pair of teammates to lead MLB in batting average and home runs since Hank Aaron (.355) and Eddie Mathews (46 HR) did it in 1959 with the Milwaukee Braves.

[52] Coincidentally, he also became the second Yankees player in a row, after Paul O'Neill in 1994, to win a batting title in a shortened season before entering contract negotiations.

[53] LeMahieu also led the AL in OBP (.421), OPS (1.011), adjusted OPS+ (177), offensive win percentage (.813), and bWAR for position players (2.8).

[55] On January 27, 2021, LeMahieu signed a six-year, $90 million deal in free agency to return to the Yankees.

[62] LeMahieu suffered a non-displaced fracture of right foot prior to the 2024 season and began the year on the injured list.