Shortly after he became prime minister, Carrero Blanco was assassinated in Madrid in a streetside bombing on 20 December 1973 by the Basque nationalist group Euskadi Ta Askatasuna (ETA) while he was returning from Mass in his car.

He had his early schooling at the Colegio Manzanedo [es] in Santoña and in 1918, at the age of 14, he followed the family military tradition by enlisting at the Spanish Naval Academy in San Fernando, Cádiz.

As a military man of conservative views he knew that he was marked; his brother José had already been detained and subsequently executed and his father died on the day of his arrest.

Following the Nationalist victory and subsequent establishment of Generalísimo Franco as Caudillo of Spain, Carrero Blanco was appointed Chief of Naval Operations in August 1939.

[7] Carrero was—as Joan Maria Thomàs puts it—"extremely faithful and submissive to El Caudillo", a polar opposite of Suñer, of whom the dictator had become weary (despite their family connection).

By that time Franco, even if he was still then the head of state and concurrent Prime Minister, had already delegated the day-to-day running of the government over to Carrero Blanco himself, owing to the former's old age and illness.

Carrero Blanco symbolized better than anyone else the figure of "pure Francoism" and without totally linking himself to any of the Francoist tendencies, he covertly attempted to push Opus Dei into power.

[13] In his first speech to the Cortes on 12 February 1974, Carrero Blanco's successor as prime minister, Carlos Arias Navarro, promised liberalizing reforms including the right to form political associations.

In addition, it received assistance from a number of right-wing paramilitary groups through Jean-Pierre Cherid (OAS), José María Boccardo (Argentine Anticommunist Alliance) and Mario Ricci (Avanguardia Nazionale).

[15] Carrero Blanco's funeral, which would be one of Franco's last public appearances, was held the following day at the Basilica of Saint Francis the Great, Madrid and he was buried at Mingorrubio Cemetery in the neighbouring municipality of El Pardo.

[25] A defender of the idea that the victory of the Francoist side in the Civil War had happened "despite" an alleged international conspiracy against the former, years later, in the 1950s, he insisted again: "this is precisely the Spanish problem, Spain wants to implement the Good, and the forces of Evil, unleashed upon the world, try to prevent her from doing it".

[27] Regarding the future of a post-Franco Spain, Carrero, along with López Rodó, envisaged and promoted the idea of an authoritarian monarchy guaranteeing the continuity of Francoism.