Born and raised in Amory, Mississippi , Moreland attended Amory High School , where he competed in baseball , football , and soccer . At Amory, he was a 2004 Louisville Slugger All-American after posting a 7–1 win-loss record with a 0.53 earned run average (ERA) as a senior, while also batting .456 and striking out just three times during the season. While in high school, Mitch played on the same team as Derek Norris. After high school, Moreland attended Mississippi State University to play college baseball for the Mississippi State Bulldogs . There, he hit .343 with ten home runs his junior season and went 2–0 on the mound with a 3.46 ERA. 
The Texas Rangers selected Moreland in the 17th round of the 2007 Major League Baseball draft . After he signed, Moreland began his professional career with the Short-Season Spokane Indians of the Northwest League . He batted .259 with 28 hits , seven doubles , one triple , two home runs and 15 runs batted in (RBIs).
The following season, Moreland joined the Class-A Clinton LumberKings of the Midwest League and hit .324 with 37 doubles, four triples, 18 home runs, 99 RBIs and two stolen bases . He was named to the Mid-Season Midwest League All-Star Team on June 17 and the Post-Season Midwest League All-Star Team on August 26.  
Moreland played in two different levels of the Rangers' organization in 2009. He started the season with the Class-A Advanced Bakersfield Blaze and hit .341 with 19 doubles, eight home runs and 26 RBIs. He was promoted to the Double-A Frisco RoughRiders where he batted .326 with 19 doubles, three triples, eight home runs and 59 RBIs. Moreland was assigned to the Arizona Fall League at the end of the season and played for the Surprise Rafters .  He was named the " Tom Grieve Minor League Player of the Year" by the Texas Rangers after the season.  
The Rangers invited Moreland to spring training in 2010.  Moreland played with the Oklahoma City RedHawks (AAA) in the 2010 season until July 29. As of July 29, he had a season batting average of .289 with the RedHawks. 
On July 29, 2010, Moreland was called up by the Rangers to take the place of Ian Kinsler, who was put on the disabled list. He achieved his first Major League hit in his first at-bat, hitting a single against Oakland Athletics pitcher Vin Mazzaro . He finished the game 2–4, with two singles, as the Rangers won 7–4.  On August 4, Moreland hit his first run of his major league career.  Along with the RBI, he went 2–5 with a run scored that night in the Rangers' 11–6 win over the Seattle Mariners . The next day, Moreland went hitless in two at-bats for the first time, although he did walk twice, but had his first multi-RBI game days later against the Yankees and his first home run on August 13, a two-run shot off of Josh Beckett of the Red Sox .
On September 26, Moreland had his first multi-home run game of his major league career, hitting his sixth and seventh home runs of the year, in a 16–9 win over the Oakland Athletics .  On October 30, 2010, Moreland hit a second inning, three-run home run off of Jonathan Sánchez to put the Rangers ahead 3–0 in Game 3 of the 2010 World Series . He was the first Rangers player in 2010 World Series to hit a home run. The Rangers eventually lost the series against the San Francisco Giants in 5 games.
On June 21, 2011, Moreland hit his first career walk-off home run off of Enerio Del Rosario of the Houston Astros . For the 2011 season, he batted .259 with 16 home runs.  That year, the Rangers entered the World Series for the second season in a row. Mitch hit one home run during the 2011 World Series against the St. Louis Cardinals , which the team lost in 7 games.
On June 9, 2012, Moreland became only the second American League batter in history ( Boston's David Ortiz being the first  ) to hit a home run ball into AT&T Park 's McCovey Cove . Moreland's 428-foot, 8th-inning blast off San Francisco Giants pitcher Ryan Vogelsong was also the first pinch-hit home run hit into McCovey Cove by an opposing player of either league. 
The 2015 season was a career year for Moreland. He was second on the team behind Prince Fielder with a .278 batting average and 85 RBIs. He was tied with Fielder for the team lead with 23 home runs.