In 1955, he gave a speech before the Cuban House of Representatives in opposition to the amnesty granted to his former brother-in-law, Fidel Castro, for his involvement in the 1953 attack on the Moncada Barracks. Rafael Diaz-Balart was elected Senator in 1958, but was unable to take office due to Fidel Castro's rise to power on January 1, 1959.
He founded La Rosa Blanca (The White Rose), the first anti-Castro organization, in January 1959. He is the father of U.S. Congressmen Lincoln Diaz-Balart and Mario Diaz-Balart, TV news journalist Jose Diaz-Balart, banker Rafael Díaz-Balart and Belen Diaz-Balart. He is the brother of Mirta Díaz-Balart, Fidel Castro's first wife. His brother, Waldo Diaz-Balart is a painter and a former actor in two movies by Andy Warhol in the 1960s. His father, Rafael Diaz-Balart was elected to the Cuban House of Representatives in 1936 and his brother-in-law, Juan Caballero, was elected the Cuban House of Representatives in 1954.