After his rookie year in 2012, Montero struggled with the Mariners in 2013 before ending his season with a 50-game suspension for his involvement in the Biogenesis scandal.

Montero was signed by the Toronto Blue Jays in 2016 and the Baltimore Orioles in 2017 but spent his time on their minor league teams.

[1] Baseball America considered Montero to be the best player available and the best power hitter in the 2006 international free agent class.

As a result of his performance, the Yankees invited Montero to spring training in 2008,[3] where he hit a home run in his only at bat before being assigned to minor league camp.

[27] Montero was honored on the International League's Postseason All-Star team,[28] and was chosen as the Scranton/Wilkes-Barre Player of the Year.

He started his first major league game that same day as the designated hitter against the Boston Red Sox at Fenway Park.

[37] On 5 September, during a game against the Baltimore Orioles, Montero hit his first two home runs of his major league career and the Yankees took an 11–10 victory.

[43] During the 2011–12 off season, the Yankees traded Montero with Héctor Noesí for Michael Pineda and José Campos.

[44] The Mariners had finished last in runs scored in the past two years,[45] and their need for a right-handed power hitter led them to trade Pineda from their depth of top-tier pitching prospects.

[48] During the season, the Mariners split his playing time between catcher and designated hitter, and he appeared in a total of 135 games.

[47][49] Montero began his 2013 season slowly as he compiled only a .208 batting average, three home runs, and nine RBIs in his first 29 games played.

[47][50] As he struggled throwing out baserunners attempting stolen bases, the Mariners played Montero as a first baseman for the first time in his professional career.

[52] After the regular season, Montero returned to Venezuela to play in the Venezuelan Professional Baseball League (VPBL).

[53] In an August game against the Boise Hawks, Montero was involved in an altercation with roving instructor Butch Baccala.

[59] Zduriencik stated: "First off, it is clear that both Jesus Montero and Butch Baccala engaged in behavior that is far below what we expect from members of our organization, including bad judgment at nearly every stage of this incident.

[63] After Montero batted .332 with 15 home runs and 68 RBIs in 84 games for Tacoma, the Mariners promoted him to the major leagues on 9 July.

[69] In spring training in 2016, Montero competed with Stefen Romero and Dae-ho Lee to be the right-handed hitting complement to Lind.

[70][71] On 27 March 2016, Montero was designated for assignment by the Mariners, and the following day, was claimed by the Toronto Blue Jays off of waivers.

[72] The Blue Jays assigned Montero to the Buffalo Bisons of the International League on 1 April, outrighting him off of their 40-man roster.

[73] In 126 games for the Triple–A Buffalo Bisons, Montero slashed .317/.349/.438 with 11 home runs and 60 RBI, and was named an International League post-season All Star.

[75] After the conclusion of the regular season, Montero was suspended for 50 games for testing positive for a banned substance.

With his wife, fitness model Taneth (nee Gimenez), Montero has a daughter, Loren, born in April 2014.