He played in Major League Baseball (MLB) for the Boston Red Sox, Arizona Diamondbacks, Miami Marlins and New York Mets.

In the 2011 season, he was named the Pac-12 Defensive Player of the Year and earned a spot on the All-Conference first team, all while hitting a .313 average.

[5] Marrero began his professional career in 2012 with Single-A Lowell Spinners of the New York–Penn League, where he posted a .268/.358/.374 slash line with 19 extra-base hits, 45 runs and 24 stolen bases in 64 games.

[6] He began the 2013 season with the Salem Red Sox and was promoted to the AA Portland Sea Dogs after hitting .256 over 85 games.

[1] Marrero began the 2014 season with Portland and, after hitting .291 over 68 games, he was promoted to the AAA Pawtucket Red Sox.

[8] He made his major league debut against the Tampa Bay Rays on June 28 at second base after Mike Napoli was ejected in the second inning.

[9] Marrero hit his first major league home run off of Caleb Cotham of the New York Yankees on September 28, 2015.

[11] On August 24, 2017, Marrero was optioned to Triple-A Pawtucket after the Red Sox acquired Rajai Davis from the Oakland Athletics.

[12] During the 2017 season, Marrero played in 71 games for the Red Sox, hitting four home runs with 27 RBIs and a .211 batting average.

[13] In his three years with the Red Sox, Marrero appeared in a total of 109 regular season games, batting .208 with five home runs and 30 RBIs.

[15] With the Diamondbacks, Marrero was involved in a rare occurrence on April 14—in a game against the Los Angeles Dodgers, he hit a ball over the left-center outfield fence with two men on base, but was ruled out for passing the runner at first base (Alex Avila); as a result, Marrero was credited with a single and two RBIs, rather than a home run and three RBIs.

[21] On June 16, Marrero was selected to the active roster and made his season debut that day as the starting third baseman against the St. Louis Cardinals, going 0-for-3.

[40] He went hitless in six at–bats across five games for the Mets, and was designated for assignment again on September 12 after Luis Guillorme was activated off of the injured list.