The use of terms with ancestral resonance through the 18th and 19th centuries continued during the 20th century, taking on a political tone that was distinctly regionalist, until 1936. In fact, the Republican Federal Party produced an autonomy statute for a Cantabrian-Castilian Federal State that year, which would include present-day Cantabria and any neighbouring areas from Castile and Asturias willing to join it. It could not be passed because of the Civil War. Following the war and the subsequent marginalization of such efforts under the Francoists regime, the use of the name of Cantabria decreased, to the point that for official purposes it was relegated to sports associations, the only arena in which Cantabria was noted as a region.

In 1963, the president of the Provincial Council, Pedro Escalante y Huidobro, proposed reapplying the name of Cantabria to the Province of Santander, as suggested in an academic report written by the historian Tomás Maza Solano. Although further steps were taken and many of the townships were in favour of the move, the petition did not succeed, mostly due to the opposition of Santander City Council. On 30 December 1981, a process that had been started in April 1979 by the Council of Cabezón de la Sal, under the presidency of Ambrosio Calzada Hernández, culminated in the granting of self-rule to Cantabria, outlined in Article 143 of the Spanish Constitution. Cantabria based its claim to autonomy on the constitutional precept that made provision for self-government for “provinces with a historic regional character”.

A Mixed Assembly formed out of provincial deputies and national members of parliament began the task of drawing up an Autonomy Statute on 10 September 1979. Following the approval of the General Courts on 15 December 1981, the King of Spain signed the corresponding Organic Law of Autonomy Statute for Cantabria on December 30 of the same year. Thus, the province of Santander broke its link to Castile, and left the former region of Castile and León to which it had belonged up to that time, together with the provinces of Ávila, Burgos, León, Logroño, Palencia, Salamanca, Segovia, Soria, Valladolid and Zamora.

On 20 February 1982, the first Regional Assembly (now Parliament) was formed, with provisional status. From this time, the former province of Santander has been known as Cantabria and has thereby regained its historic name. The first home-rule elections were held in May 1983. The 4th Legislature (1995–1999) brought into effect the first great reform of the Autonomy Statute of Cantabria, approved by all the parliamentary groups.