On May 22 of that year, he had his first professional fight in his hometown, Albuquerque New Mexico USA, knocking out Silverio Porras in two rounds.
Romero won five more bouts in a row, including a victory over former Alex Sanchez world title challenger Orlando Malone, before having his first chance to fight for a belt: On May 5, 1994, he knocked out Brian Lonon in two rounds to win the NABF regional Flyweight title.
On April 22, 1995, he became the IBF's world Flyweight champion with a twelve round unanimous decision over Francisco Tejedor, at the MGM Grand Arena, in Las Vegas.
Romero suffered a 7th round TKO loss to Salazar, in what Ring Magazine heralded as the "upset of the year" for 1995.
He bounced back with a first round knockout victory over former WBO world Flyweight champion Jose Quirino.
On July 18, 1997, the long-awaited bout finally took place, with Tapia winning a close twelve round unanimous decision.