After having endured years of military training, Juan Carlos credited Fernández Miranda with being the first of his tutors to teach him to rely on independent thinking.

He served as interim Presidente del Gobierno (prime minister) for a few weeks in December 1973, after the assassination of Luis Carrero Blanco.

He retained Arias Navarro as prime minister but, in a nod to his political mentor, named Fernández Miranda speaker of the Cortes (the legislature) and president of the Consejo del Reino (Council of the Kingdom) in the transition government.

Upon Arias Navarro's resignation in 1976, Spain was still operating under Francoist law; it was Fernández Miranda's job, as head of the Council of the Kingdom, to suggest three names to the king for a new political leader.

Following Suárez reforms with which he disagreed—such as the legalization of the Communist Party of Spain and increasing tolerance of decentralization – the speaker resigned from the Cortes prior to the first election, 15 June 1977.