De Jesús debuted as a professional in 1969, he won his first twenty fights, thirteen by knockout. He then stepped up in class, for the first time, when he boxed future world title challenger
Josue Marquez in 1971, beating him in a twelve-round decision to claim the Puerto Rican national Lightweight championship.. His next fight was a fourth-round knockout victory over Victor Ortíz. After that, there was a rematch with Marquez, who was beaten again, also over twelve rounds, to retain the Puerto Rican Lightweight title. Next came his first international fight, in
Caracas,
Venezuela, against the future four-time world title challenger Leonel Hernandez. De Jesús won the ten round fight by unanimous decision in what was the start of a four fight tour of Venezuela. That Venezuelan campaign ended with a ten-round decision loss against former world champion
Antonio Gomez in Caracas. 1972 was a pivotal year in de Jesús' career. He won six fights in a row, including a twelve-round knockout win in a third fight with Marquez to again retain the Puerto Rican Lightweight title, and a ten-round decision over Doug McClendon. Despite all the wins, he was virtually unknown to most boxing fans. That changed quickly in his last fight of 1972 against the undefeated new world's
Lightweight champion
Roberto Durán at the
Madison Square Garden arena. In a televised bout that marked the beginning of the "Durán - de Jesús trilogy", de Jesús dropped Durán in round one and went on to inflict Durán's first defeat in a ten-round decision. In 1973, he was rewarded for his efforts, receiving a chance to challenge
Ray Lampkin for the
North American Boxing Federation lightweight belt. He won the vacant title by beating Lampkin in a twelve-round decision. He went on to beat Johnny Gant and Raul Montoya in ten-round decisions and beat Lampkin by decision in a rematch in New York. He finished 1973 with a first-round knockout win over fringe contender
Al Foster. He began 1974 by knocking out former world Jr.
Welterweight champion
Alfonso "Peppermint" Frazer in ten rounds in
San Juan, Puerto Rico, after which he traveled to
Panama City to receive his first world title shot and, at the same time, face Durán in the second fight of their trilogy. He once again dropped Durán in round one, but this time Durán rebounded and dominated the bout, retaining the title in an eleventh-round knockout. He recovered from that defeat with two more wins before the end of the year. In 1975, he went up in weight briefly, and after beating Jesse Lara by a knockout in three, he returned to Panama City to challenge
Colombia's
Antonio Cervantes for the world's Jr. Welterweight title, losing in a fifteen-round decision. He beat Rudy Barros by knockout in round five to end that year, and started 1976 by beating Valentin Ramos by knockout in round two. Next came his third world title try when the
WBC's world Lightweight champion
Ishimatsu Suzuki of Japan traveled to
Puerto Rico to defend his title against de Jesús. The third time proved to be the charm for de Jesús, who won the world title by beating Suzuki in a fifteen-round decision. He retained the title against Hector Medina with a knockout in round seven. De Jesús admitted publicly to using drugs during his boxing career. He began using cocaine and heroin early in his boxing career with an older brother, Enrique. In 1977, he retained the title against Buzzsaw Yamabe by knockout in round six and against Vicente Mijares Saldivar by knockout in round eleven. 1978 began with the third and final chapter of his trilogy with Durán. In a title unification bout in
Las Vegas, which displayed Durán at the peak of his power, Durán systematically broke down de Jesús resulting in a twelfth-round knockout. De Jesús rebounded with three wins before the end of that year, including one over former world title challenger
Edwin Viruet. In 1979, he had two more wins, including one over Jimmy Blevins. After beating
José Vallejo by a knockout in round seven in San Juan to start 1980, he traveled to
Bloomington, Minnesota, to challenge
Saoul Mamby for Mamby's WBC world Jr. Welterweight title, in the major supporting event of the
Larry Holmes-
Scott Le Doux world heavyweight championship bout's
undercard. In what turned out to be his last fight, he was beaten by a knockout in thirteen rounds. His record was 57 wins and 5 losses, with 32 wins by knockout. ==Professional boxing record==