Montenegro has been involved in show business since he was a small child, being chosen in 1984 to act in two Radio Caracas Television telenovelas, "El Analisis" and "La Ciudad Muerta" ("Ghost Town"), both of which had been written by the well-known Venezuelan writer and politician, Rómulo Gallegos.

In addition to that, Montenegro obtained a second place in the prestigious "Festimagico Infantil" ("Magic Children's Festival") talent show, which was held by Venevisión.

One of the telenovelas he made that year was "La Intrusa", considered a classic by Latin American critics.

1988 was a year of firsts for Montenegro, as he debuted on radio with a talk show named "Tren Fantasia" ("Fantasy Train"), and also as a show host, on Radio Caracas Television's "Festival Fantastico Infantil" ("Children's Fantastic Festival").

He joined Mexico's Adrian Olivares, who had previously become the first non-Puerto Rican member of Menudo and Spain's Edward Aguilera.

Jonathan has never mentioned any specific reasons as to why he left, but by the time he did, he had already become a teen idol across Latin America and in Spain, where he toured and had to schedule a special autograph and photo session with his Madrid fans before leaving the European country.

From 1994 to 1995, Montenegro left show business periodically, concentrating on getting his high school diploma and taking English classes in the United States.

He began to produce "Tu Generacion", a radio show geared towards Venezuelan heavy metal music fans.