1980–81 Segunda División B

The 1980–81 Segunda División B was the 4th season of Segunda División B, the third highest level of the Spanish football league system, since its establishment in 1977. First and 2nd in each group were promoted to Segunda División, and the bottom three were relegated to the Tercera División.

Group 1
A total of 20 teams will contest the group, including 2 relegated from the Segunda División and 4 promoted from the Tercera División.

Promotion and relegation
Teams relegated from 1979–80 Segunda División Teams promoted from 1979–80 Tercera División
 * Celta de Vigo
 * Deportivo de La Coruña
 * SD Compostela
 * San Sebastián CF
 * RSD Alcalá
 * Gimnástica Arandina

Teams
Teams from Aragon, Asturias, Basque Country, Canary Islands, Castile and León, Galicia, La Rioja and Madrid.

Group 2
A total of 20 teams will contest the group, including 2 relegated from the Segunda División and 4 promoted from the Tercera División.

Promotion and relegation
Teams relegated from 1979–80 Segunda División Teams promoted from 1979–80 Tercera División
 * Algeciras CF
 * Gimnástico de Tarragona
 * RCD Mallorca
 * Cartagena FC
 * FC Andorra
 * Mérida

Teams
Teams from Andalusia, Andorra, Balearic Islands, Castilla–La Mancha, Catalonia, Extremadura, Region of Murcia and Valencian Community.