Baloncesto León was founded by José Antonio Moirón García, Enrique Emperador Marcos, Juan Carlos Rodríguez Villanueva, Lisardo Mourelo González and Alberto Sobrín Martínez in León on 20 May 1981.

After four years playing in the third tier, Baloncesto León was promoted to Primera División B, the second division.

In the middle of the 1988-1989 season, the coach Mariano Parra was sacked because Baloncesto León was in relegation posts.

Then Baloncesto León signed Gustavo Aranzana, the coach of Cajapalencia, a team which was playing in Segunda División.

Baloncesto León managed to leave relegation, and the next year, led by Xavi Fernández, was promoted to the ACB for first time in its history.

In 2005–2006, Baloncesto León was, along with CAI Zaragoza, the highest-ranking team in the LEB regular season.

In the playoff, Baloncesto León easily defeated Palma Aqua Mágica and reached the semifinal round.