Mateo played his first professional season, in American baseball, with their Single-A Charleston RiverDogs in 1996.

In 2009, he played in the Mexican League for the Broncos de Reynosa, his most recent professional season.

He was once regarded as the top prospect in the Texas Rangers system and was frequently rumored to be involved in many high-profile trades.

On June 2, 2000, Ruben Mateo broke his leg trying to beat out a ground ball to first base.

Mateo won the most valuable player award during the 2013 Mexican League season while playing for Delfines del Carmen.