Martínez was signed by the Toronto Blue Jays in 1984, and spent several years in the minors before making his major league debut in 1992.

He was recognized for his standout hitting with a Best Nine award in 1997, and his round appearance made him a popular figure among fans, who gave him the nickname Maruchan.

Martínez spent the beginning of 1999 playing in the Mexican League, but was called back to Japan by the Yomiuri Giants, who signed him in June.

He continued his hitting prowess by batting .324 with 16 homers and 56 RBIs, but his poor fielding often required a defensive substitution late in games.

Martinez retired after his contract expired at the end of 2001, and he later joined the Central League's Chunichi Dragons as a scout in 2006.