Thoroughbred racing is in Jimmy's blood. A native of Bayshore, Long Island , Jimmy was introduced to racing through his father, Hall of Fame trainer H. Allen Jerkens – The Chief. After high school graduation, Jimmy worked for his father as an assistant for two decades, going out on his own in 1997.

Among his many accomplishments, Jimmy tied Gary Contessa as leading trainer at the 1999 – 2000 Aqueduct inner track meet. He trained Artie Schiller to win the Breeders' Cup Mile at Belmont in 2005, and has conditioned noted stakes winners such as Big EE, Lager, Thomas Jo, and Silentlea. His barn currently holds such runners as Smokey Glacken , Voodoo, Snake Mountain and Message Red.