José Antonio Rivera began his professional boxing career on February 26, 1981, after a long and successful amateur boxing career, knocking out Humberto Maldonado in the first round at Trujillo Alto, Puerto Rico. He posted two more wins in a row, one by knockout, then lost for the first time as a professional, beaten by Herminio Adorno by a decision in five rounds on May 22. Rivera avenged that loss with a first-round knockout of Adorno on July 9, in Trujillo Alto.