Javier Castellano was born October 23, 1977 in Maracaibo, Zulia State, Venezuela. Castellano began his riding career in La Rinconada and Santa Rita racetracks (Venezuela). In June 1997 moved to the United States where rode at race tracks in southern Florida until 2001 when he moved to race on the New York State racing circuit.
In 2004, Javier Castellano got his big break when he was the rider for Frank Stronach's colt Ghostzapper on whom he won several major races including the 2004 Breeders' Cup Classic. Ghostzapper was voted the 2004 Eclipse Award for Horse of the Year and named the World's Top Ranked Horse. In 2006, Castellano rode Bernardini for Mohammed bin Rashid Al Maktoum's Darley Racing. Among his wins with Bernardini was the Preakness Stakes, and the Jockey Club Gold Cup.
Castellano received his first Eclipse Award for Outstanding Jockey in 2013. He finished the year with purse earnings of over $26.2 million, surpassing the season mark set by Venezuelan jockey Ramon Dominguez in 2012.