The Chicago Cubs selected LeMahieu in the second round of the 2009 MLB draft with the 79th overall selection.[14] He played for the Peoria Chiefs of the Single–A Midwest League in 2009 after the draft. In 38 games, he hit .316 with 30 runs batted in. He spent the 2010 season with the Daytona Cubs of the High–A Florida State League, batting .314 with 73 runs batted in and 15 stolen bases in 135 games, going on to earn a Florida State League post-season All-Star selection.[15] LeMahieu began the 2011 season with the Tennessee Smokies of the Double–A Southern League.
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. He did not stay in the game, a 12–7 loss to the Houston Astros.[citation needed] The Cubs demoted LeMahieu to the Iowa Cubs of the Triple–A Pacific Coast League (PCL) in June. He returned to the major leagues in September[17] and would be honored as an MiLB.com Organization All-Star for the 2011 season.[18]
On December 8, 2011, the Cubs traded LeMahieu and Tyler Colvin to the Colorado Rockies for Casey Weathers and Ian Stewart.[19] He began the 2012 season with the Colorado Springs Sky Sox of the PCL.
LeMahieu with the Rockies in 2013
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.[21] On August 14, he recorded a career-best four hits in a 9–6 Rockies win over the Milwaukee Brewers and in his first game against his former team, the Chicago Cubs, LeMahieu registered three hits in four at bats. Later in August, LeMahieu wrote his name into the record books, as he recorded 12 assists in a 9-inning victory against the Los Angeles Dodgers on the 28th.[22] This mark tied a record held by several players.
In 2014, LeMahieu batted .267/.315/.348 with five home runs in 494 at bats. Defensively, he had an ultimate zone rating of 11.0, which was first in the National League (NL) and third in the majors. He won his first Gold Glove[23] with 16 Defensive Runs Saved[24] and led the majors with 99 double plays.[23]
LeMahieu was the starting second baseman for the NL in the 2015 All-Star Game; this was LeMahieu's first All-Star selection. For the season, he batted .301 and led the majors in percentage of opposite field hits (39.0%), while seeing the highest percentage of fastballs of all MLB hitters (66.9%).[25][26]
In 2016, LeMahieu won the NL batting title after batting .439 in August and .363 in September.[27] His .348 season average led all of MLB. For the season, he had the highest batting average on balls in play (.388) of all major league players, and again led the majors in percentage of balls hit to the opposite field (37.9%).[28][29]
LeMahieu was selected to the 2017 MLB All-Star Game as an injury replacement for Dee Gordon.[30] He batted .310 and for the third consecutive year led the majors in percentage of balls hit to the opposite field (38.3%), while seeing the highest percentage of fastballs of all MLB hitters (67.0%).[31][32] Also again in 2017, LeMahieu collected the NL Gold Glove for second basemen.[33] Additionally, he won the Fielding Bible Award for all major league second basemen.[34]
In the 2018 season, LeMahieu hit a career-high 15 home runs while batting .276/.321/.428. He was tied for seeing the highest percentage of fastballs of all MLB hitters (63.6%).[35][36] In addition to an increase in power numbers, his defensive excellence continued. LeMahieu finished the 2018 season with a 19.5 SDI (SABR Defensive Index) highest of all NL players, and his 2.2 defensive WAR[clarification needed] was eighth best among all of MLB. The .993 fielding percentage, .859 zone rating and 18 defensive runs saved were best for all NL second basemen. He earned both a third Gold Glove and a third Wilson Defensive Player of the Year Award.[37]
On January 14, 2019, LeMahieu signed a two-year, $24 million deal with the New York Yankees.[38] The Yankees anticipated using LeMahieu as a utility infielder.[39] He put together a 14-game hitting streak from June 14 to 30 (including 6 consecutive multi-hit games from June 23–30).[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.[citation needed]
Due to injuries in the team, he spent time at first, second, and third base throughout the season.[1] It was the first time he played in multiple positions since 2014, but did not cover shortstop that season. He was also the first Yankees player to ever make 25 starts in each of the three different infield positions.[42] During the playoffs, he played exclusively at first base. 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. However, José Altuve would hit a walk-off home run in the bottom of the inning, eliminating the Yankees.
LeMahieu finished the 2019 season batting .327 with 26 home runs and 102 runs batted in during 145 games.[43] He set new career highs in hits (197), doubles (33), home runs, runs batted in, runs scored (109), runs created (115), slugging percentage (.518), adjusted OPS+ (135), isolated power (.191), total bases (312), offensive WAR (5.2), fWAR (5.4), and bWAR (5.9). He had the lowest pull percentage of all major league batters (27.9%) and posted remarkably consistent stats all-round (his lowest monthly batting average was .282 in July, while his home/road and pre/post All-Star splits were .338/.318 and .336/.316 respectively).[44] Additionally, besides ranking second in the American League in batting average behind Tim Anderson, he became the first Yankee to qualify for the batting title with a .300+ batting average since Canó in 2013, and posted the highest batting average for a Yankee player since Derek Jeter hit .334 in 2009. LeMahieu was awarded the Silver Slugger Award for the first time in his career,[45] was named to the inaugural All-MLB First Team for second base, and finished fourth in the AL MVP voting behind Mike Trout, Alex Bregman, and Marcus Semien.[46]
LeMahieu did not appear in the Yankees' 2020 Opening Day starting lineup after recovering from COVID-19.[47] After a four-hit game against the Atlanta Braves, he was batting .431 in 65 at-bats.[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.[49] LeMahieu was activated from the injured list on August 29.[50]
LeMahieu ended the season with a .364 batting average, which was the highest in the American League. He was the fourth Yankee to lead the majors in hitting, the ninth Yankee to win an AL batting title, and the first to do so since Bernie Williams in 1998. LeMahieu was also the second player ever to win a batting title in each league (LeMahieu led the NL in 2016 with a .348 average playing for the Colorado Rockies) following Ed Delahanty, who hit .410 for Philadelphia (NL) in 1899 and .376 for Washington (AL) in 1902.[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). He won his second consecutive Silver Slugger Award[54] and finished third in AL MVP voting behind José Abreu and José Ramírez.[55]
On January 27, 2021, LeMahieu signed a six-year, $90 million deal in free agency to return to the Yankees.[56] On May 7, 2021, during a game against the Washington Nationals, LeMahieu recorded his 300th career hit with the Yankees, doing so in his 225th game. This was the second fastest in team history behind Joe DiMaggio, who accomplished the feat in 200 games.
In 2021 he batted .268/.349/.362, and had the lowest pull percentage in the major leagues (at 24.8%), and the highest opposite field percentage (at 35.8%).[57]
In 2022, LeMahieu batted .261/.357/.377 in 467 at bats with 12 home runs and 46 RBIs.[58] 60.1% of the pitches to him were fastballs, the highest percentage of those to any major leaguer.[59] He swung at a lower percentage of pitches in the strike zone (54.7%) than any other major league batter.[60] He became the first recipient of the American League Gold Glove Award for a utility player.[61]
LeMahieu played in a total of 136 games for the Yankees in 2023, batting .243/.327/.390 with 15 home runs and 44 RBI. He had experienced struggles while working under hitting coach Dillon Lawson, but saw a spike in production after Lawson was replaced midseason by Sean Casey.[62]
LeMahieu suffered a non–displaced fracture of right foot prior to the 2024 season and began the year on the injured list.[63] His rehabilitation was prolonged after he continued to experience soreness in the same foot.[64] LeMahieu was activated from the injured list and returned to the Yankees' lineup on May 28, 2024.[65]