Unión was founded in 1948 as a football club, but it expanded into several different sports, including basketball, where the team currently plays at Torneo Nacional de Ascenso (TNA), the second division of Argentine basketball league system.
Basketball was added as sport in 1950. The club won its first official title, the Asociación Rafaelina de Básquetbol championship, in 1987 being coached by Roberto Vico.[citation needed]
In 1991 Unión promoted to Liga Nacional B (currently Torneo Nacional de Ascenso, the second division of Argentine basketball). The club spent two seasons in the Nacional B until the team had to leave the tournament due to financial problems. In 2005 Unión won another title promoting to Nacional de Ascenso.[citation needed]