Hernandez was born Javier Manuel Hernandez, Jr. in Montebello, California, the son of Isis (nee Maldonado), a secretary and accountant, and Javier Hernandez, Sr., a mechanic. He has a younger sister, Amelia, and two older brothers, Michael and Gabriel. Hernandez is a fourth-generation Mexican American. He attended Don Bosco Technical Institute in Rosemead, California, but transferred to Schurr High School in Montebello, California his senior year. While riding an elevator in a high rise in Los Angeles, Hernandez was approached by talent manager Howard Tyner who suggested Hernandez had what it took to have a successful career in Hollywood. He enrolled Hernandez into acting school and sent his pictures to casting agents.