Espinosa turned professional in 1984. In 1989, he won the WBA Bantamweight title by knocking out Khaokor Galaxy in the first round. He was trained by Dee Pooler now of Pacific Rim Sports. He defended the title twice before losing it to Israel Contreras by a 5th round knockout in 1991.
In 1995, he won the WBC Featherweight title by outpointing Manuel Medina. He defended the title seven times before losing the belt in 1999 to Cesar Soto who won by unanimous decision. The following year, he challenged Guty Espadas Jr for the Vacant WBC Featherweight Title, but was outboxed and lost a technical decision after their fight was stopped after a clash of heads. Espinosa retired in 2005 after being knocked out by Cristobal Cruz.
Promotional disputes left Espinosa with little, and he retired in 2005 after a public outcry for him to stop fighting. He currently is working as a stocker at Costco, a membership wholesale store chain.