He has won the Kentucky Derby three times, riding War Emblem in 2002, California Chrome in 2014, and American Pharoah in 2015.

[2] He joined Ron Turcotte as the only jockeys to win five of the six jewels of the Triple Crown spread over two consecutive years.

[4][5] Within a few years, Espinoza was racing Thoroughbreds at Mexico City's track, Hipódromo de las Américas.

He moved to Northern California in 1992,[7] where by 1994 he was the leading apprentice rider at the Bay Meadows and Golden Gate Fields racetracks.

He hired a new agent in January 2013, Brian Beach, and with a change in motivation[9] went on to obtain his 3,000th career win, aboard Flashy Delight, on May 31, 2013, at Betfair Hollywood Park in Inglewood, California.

[6] On June 7, Espinoza's 6 for 6 streak aboard California Chrome came to an end when, due to an injury sustained right out of the starting gate, the Triple Crown contender finished in a dead heat for fourth place in the Belmont Stakes.

[17] In the fall of 2014, Espinoza also became the regular rider of American Pharoah, trained by Bob Baffert and owned by Ahmed Zayat.

[19] The colt was scratched from the Breeders' Cup Juvenile,[20] but the pair reunited in 2015 with wins in the Rebel Stakes and Arkansas Derby.

[26] For 3 years, he held the distinction of being the last jockey, and the oldest, to sweep the Triple Crown until Mike Smith did it aboard Justify in 2018.

[29] Several weeks after the accident, he continued to have trouble shaving, walking and getting out of bed, and lacked feeling in his left arm.