Estrada was born on April 19, 1937 in Tondo, Manila to Emilio Ejercito, Sr., a former Chief Sanitary Engineer of Manila, and Maria Marcelo. He has two brothers, Antonio Ejercito (1932-2005) and Emilio Ejercito, Jr. (also known as "George Estregan") (1928-1999). He studied at the Ateneo de Manila University but was expelled for unbecoming conduct. He enrolled at the Mapua Institute of Technology but dropped out before finishing college to pursue a career in acting.In 1968, Estrada ran for mayor of the municipality of San Juan, but without any background in politics, he lost to Dr. Braulio Sto. Domingo. His camp filed an electoral protest against Sto. Domingo and was favored by the court. Estrada was proclaimed mayor of San Juan in the following year. This was the start of his sixteen-year tenure as San Juan mayor.
When Corazon Aquino assumed the presidency in 1986, all local government officials suspected of malfeasance and anomalies, Estrada included, were removed from office. He ran for senate the following year won a seat under the Grand Alliance for Democracy (GAD) party.
