According to records, Villaflor began his career as a professional boxer when he was only thirteen years old, on October 1, 1966, beating Flash Javier by decision in four rounds.
On April 25, 1972, Villaflor was given his first opportunity at a world title, when faced with WBA and Lineal Jr. Lightweight champion Alfredo Marcano of Venezuela.
On March 12, 1973, Villaflor lost his title for the first time, being beaten on points by Japan's Kuniaki Shibata over fifteen rounds in Honolulu.
Next for Villaflor was a widely expected fight across Asia, as he met Japan's top rated challenger, Apollo Yoshio, on March 14, 1974, at Toyama.
Villaflor retained the title twice more, then met Samuel Serrano for the first time, on April 13, 1976, in Honolulu, and the two combatants fought to a fifteen-round draw.
After winning a non-title bout by knockout, Villaflor traveled to Puerto Rico for the rematch, held on November 16, at Hiram Bithorn stadium, in San Juan.