He has played for the Chicago White Sox, San Diego Padres and Tampa Bay Rays in MLB and Pinar del Rio of the Cuban National Series.

His nickname, given to him by former White Sox manager Ozzie Guillén, is "the Cuban Missile" due to his tall, slim physique and combination of speed, power, and strong throwing arm.

In seven years of baseball in the Cuban National Series, Ramírez spent most of his time playing shortstop and outfield for Pinar del Rio.

He auditioned for many baseball teams before coming to an agreement on a four-year, $8 million contract with the Chicago White Sox on December 21, 2007.

[2] Ramírez made his MLB debut on March 31, 2008 against the Cleveland Indians, finishing the game 0-for-4 as the starting center fielder.

[5] Ramírez hit his first major league home run on May 16,[4] off San Francisco Giants reliever Billy Sadler.

[7] On September 19, Ramírez hit his third grand slam of the season off of pitcher Brian Bannister of the Kansas City Royals, tying an American League rookie record set by Shane Spencer of the New York Yankees in 1998.

[10] During his first season in the Majors, Ramírez excelled both offensively and in the field, despite primarily playing second base instead of his customary shortstop position.

[11] He finished in second place in the voting for American League Rookie of the Year honors, losing to Evan Longoria of the Tampa Bay Rays.

[11][15] On January 31, 2011, Ramírez signed a four-year, $32.5 million contract with the White Sox that included a club option for a fifth year.