Mike Oltwas born on August 27, 1988, in New Haven, Connecticut, and grew up in Branford, Connecticut. He attended Branford High School, where he played as the starting shortstop for all four years. In 2006, he helped lead his team to the Connecticut state championship. He finished high school holding the school record for hits (115) and had a career batting average of .475. He earned three selections as All‑League and All‑State, and was a two-time MVP in the Legion state and regional tournaments. After high school, he enrolled at the University of Connecticut and played for the Connecticut Huskies. In his freshman year, he earned Freshman All‑American honors and set a UConn record with 61 RBIs in 2008 while batting .318 and hitting 13 home runs. He also stole 18 bases in 20 attempts.
During the summers of 2008 and 2009, Olt played collegiate summer baseball with the Orleans Firebirds in the Cape Cod Baseball League. He also spent time with the Danbury Westerners in the New England Collegiate Baseball League in 2008, gaining experience against strong college competition.
Mike Olt was picked by the Texas Rangers in the supplemental first round (49th overall) of the 2010 MLB Draft after playing college baseball at Connecticut. He began in the minor leagues and quickly gained attention. In 2012, he led the Double-A Texas League with 28 home runs and received a call-up to the major leagues. He debuted on August 2, 2012, with the Rangers and recorded his first hit in his first at-bat.
In July 2013, Olt was traded to the Chicago Cubs as part of a deal for pitcher Matt Garza. He earned a spot on the Cubs’ roster in 2014 and hit 12 home runs in 89 games. He stayed with Chicago into 2015 but struggled at the plate.
In September 2015, the Chicago White Sox claimed him off waivers. During that season, he made history by becoming the only player to hit home runs for both Chicago teams in a single year. The White Sox released him in March 2016.
Olt then signed minor league contracts, including with the San Diego Padres in 2016 and the Boston Red Sox in 2017–2018. In 2019, he briefly joined independent and Mexican league teams before retiring on October 25, 2019.
Over his MLB career, he appeared in three seasons (2012, 2014–2015), playing for the Rangers, Cubs, and White Sox. He had 352 at-bats, a .168 batting average, 16 home runs, and 43 RBIs.