The network operates studios across Spain, providing local and regional news and information, with each location producing between 2 and 3.5 hours of programming daily.

However, during General Francisco Franco's dictatorship (1939–1977) and the initial stages of Spain’s transition to democracy, the network was restricted from airing national news programming, limited instead to twice-daily relays of government-controlled news bulletins by Radio Nacional de España.

On September 25, 1940, ownership of Unión Radio transitioned to the newly formed Sociedad Española de Radiodifusión ("Spanish Broadcasting Company"), which rebranded the network as Cadena SER.

Cadena SER played a pivotal role during Spain’s transition to democracy post-Franco and in the lead-up to and aftermath of the adoption of the Spanish Constitution of 1978, particularly notable for its coverage of the attempted coup of 23 February 1981.

As of 2021, Cadena SER boasted 4,367,000 listeners according to the first wave of the General Media Study (EGM), marking its highest audience since 2017 and significantly surpassing competitors such as Cope and Onda Cero.