How did Juan Carlos become king of Spain in 1975?

Juan Carlos became king of Spain in 1975 as a direct result of the political framework established by General Francisco Franco during his long-standing dictatorship.12

Following the Spanish Civil War, Franco’s regime enacted a series of Fundamental Laws that declared Spain a monarchy. Although Spain remained without a ruling monarch for decades, a 1947 law officially abolished the republic and established the state as a "representative monarchy," with Franco acting as a regent for life.231

In 1969, Franco formally designated Juan Carlos—the grandson of the last king, Alfonso XIII—as his official successor. This decision was ratified by the Cortes on July 22, 1969. Juan Carlos, who had received his education in Spain under Franco's supervision, accepted the designation after previously maintaining that his father’s claim to the throne preceded his own.13

Upon Franco's death on November 20, 1975, Juan Carlos acceded to the throne two days later, on November 22, 1975, effectively restoring the House of Bourbon to the Spanish monarchy.124