A native of Caracas, Venezuela, Dominguez won the Eclipse Award as the outstanding jockey in 2010 and 2011 and led all riders in purse money earnings both years. He began riding show jumpers at the age of 16 and about a year later made the switch to Thoroughbred racehorses. After graduating from high school, he moved to the U.S. and started his riding career in 1996 at Hialeah Park in Florida.
In 2000, Dominguez relocated to the Mid-Atlantic region where he became the dominant rider in Maryland and Delaware. He led the nation in victories in 2001 and 2004 and was second in 2006. That success led him to New York, and he has become a top rider on the New York Racing Association circuit of Aqueduct, Belmont Park and Saratoga. Among the top horses he rode in 2011 were Horse of the Year Havre de Grace and champions Hansen and Stacelita.