Gary Mandella was born in Redlands, California, and began working for his father, Hall of Fame trainer Richard Mandella, at age 12 during his summer breaks from school. He went on to gain valuable experience through summer internships with Charlie Whittingham in 1993 and Claiborne Farm in 1994.

In 1999, Gary joined the newly formed broadcasting network TVG, where he worked through 2001. He returned to work for his father in 2002 while also training horses on his own. From 2010 to 2015, he resumed part-time broadcasting duties with HRTV.

As a trainer, Gary’s horses have earned more than $12 million in purses and won more than 200 races. He lives in Pasadena with his wife, Audra. His son, Joshua, attends the University of Arizona, and his stepdaughter, Jacy, attends Tarleton State University in Texas.