Avellanet would soon join the United Artists record label, making what would be his only attempt at a cross-over into the American pop genre, with the album In a Little Spanish Town. His fourteen other records under that label were recorded in Spanish. In 1965, under United Artist, he recorded the album titled Chucho Avellanet Baladas Spanish Sounds in Country Music produced by LeRoy Holmes. This album featured a choice sampling of the better tunes that had emerged from the world of country and Western music at the time including It Makes No Difference Now (No Me Importa) by Jimmy Davis, and Sinceridad (“Are you Sincere?”) by Wayne Walker/Gil Veda.

1972 was a very eventful year for Avellanet, who represented his country finishing in fourth place at that year’s Festival OTI in Spain. Then, Avellanet made history by becoming the first Hispanic to perform at the Miss Universe contest, held that year in the Puerto Rican beach town of Dorado.

In 1988, Avellanet came back to the headlines, but not precisely because of his own, personal success: His nephew Roberto Alejandro Avellanet Negrón was chosen as the newest member of Menudo. Roberto followed in his uncle’s footsteps, becoming a major teen-idol in Puerto Rico within months of his joining the teenaged boy band.

In 1989 he starred in “Papi”, a prime-time sitcom on “WAPA-TV”, Puerto Rico’s Channel 4, in which he played the superintendent of a condominium with eccentric residents. He sang the show’s intro theme song called “Yo Soy Como Soy” (“That’s Who I am”). He returned to sitcoms in 2012 with “Papi en Casa (“Dad at Home”), on “WLII-TV”, Channel 11, Puerto Rico’s “Univision” affiliate, in which he played a grandfather.

In 1994, Avellanet, Lucecita Benítez and Lissette Alvarez rejoined forces for a one-night-only concert.

In 2010, Avellanet performed at the opening and closing ceremonies of the 2010 Central American and Caribbean Games, held in Mayagüez. Later in the year he publicly announced that he was undergoing chemotherapy for treating Non-Hodgkin’s lymphoma. Stating that his prognosis is good, he nevertheless asked for privacy while undergoing treatment.

On stage in San Juan during the 1980s, Avellanet appeared as “El Lince” in the musical “La Verdadera Historia de Pedro Navaja”, a Caribbean-set adaptation of “The Beggar’s Opera”, and “Father Silvestre” in the Puerto Rican production of “El Diluvio que Viene” (the Spanish-version of the Italian musical “Aggiungi un posto a tavola”). He returned to the theater in Puerto Rico in 2014, in a Spanish-language production of “Shear Madness” (“Con los Pelos de Punta”)