The 1979–80 Segunda División B was the 3rd season of Segunda División B, the third highest level of the Spanish football league system, since its establishment in 1977.
A total of 20 teams will contest the group, including 2 relegated from the Segunda División and 4 promoted from the Tercera División.
Teams relegated from 1978–79 Segunda División Teams promoted from 1978–79 Tercera División Teams from Aragon, Asturias, Basque Provinces, Canary Islands, Galicia, León, New Castile and Old Castile.
A total of 20 teams will contest the group, including 2 relegated from the Segunda División and 4 promoted from the Tercera División.
Teams relegated from 1978–79 Segunda División Teams promoted from 1978–79 Tercera División Teams from Andalusia, Balearic Islands, Catalonia, Extremadura, New Castile and Valencia.