He most recently pitched for the Coastal Bay Thunder of United League Baseball in 2010.

Born in Santo Domingo, Dominican Republic, Martínez was signed as a 16-year-old amateur free agent by the Brewers in 1996.

He posted a 0–3 record with a 9.92 ERA in four starts for Milwaukee, allowing 18 runs on 25 hits, while striking out 10 and walking 15 in 16.1 innings of work.

Following his majors stint, Martínez played in the St. Louis Cardinals and Colorado Rockies minor league systems in 2004.

While in St. Louis, he was traded to the Rockies the same transaction that brought Larry Walker to the Cardinals.