Castillo played in the Orquesta Mandolina in Puerto Rico, but his main calling was as an actor. He studied at the University of Puerto Rico, graduating in arts.
Castillo enjoyed much success in Puerto Rican television during the 1950s, being one of the first super-stars and teen idols of Puerto Rican tv. He worked at Canal 2's productions.
Castillo moved to Mexico during the 1960s, working at several Televisa productions. The new exposure made him famous accross Latin America, and he became a gossip magazine favorite. In 1970, Braulio Castillo was attacked by robbers, who almost killed him, but he was able to survive the attacks.
During the 1980s, Castillo began to suffer of failing health. His son, Braulio hijo, followed in his footsteps by becoming a teen-idol in Puerto Rico.
Nevertheless, Castillo is still semi-active in Puerto Rican public life.