Willie Martinez is known in the business as "Chillie Willie," because of his "chill" demeanor in riding.
Martinez was born in Santurce, San Juan, Puerto Rico, but emigrated to the United States in 1988 to work as a hotwalker and groom fat Finger Lakes Race Track in Farmington, New York.
He began riding professionally in 1989 and got his first win that year at Tampa Bay Downs. During his career, Martinez has won riding titles at, Ellis Park, Tampa Bay Downs, Turfway park, Keeneland and Hialeah. His nine titles at Turfway Park in Florence, Kentucky is more than any other jockey in the track's history. At the same track, he also rode seven winners on July 6, 1993.
Martinez also partakes in helping bring awareness to the sport regarding issues such as jockey rights. Matters on the constant lapses over health insurance, and weight increase tolerance in the tracks (to just name a few). Martinez alongside other professional riders were interviewed for an HBO documentary Jockey: America Undercover, series back in 2004 for their opinion on the sport.