Grau was no longer the candidate of choice among the Auténticos; they chose Prío as his successor.  Prío won, beating Ricardo Núñez Portuondo by 30,000 votes.

During his Presidency, Prío created an Agricultural and Development Bank to be lead by Justo Carillo.  He also began a program for public works.

In 1952, Fulgencio Batista began planning to overthrow Prío.  A large conspiracy involving many members of the army put its plan into action that year.  When Batista began taking over bases, Prío had to decide what to do.  Some troops were still loyal to him, and the university students supported the constitutional government.

Instead of resisting Batista, Prío fled to the Mexican embassy with other leaders of the government.  Arms promised to the students never arrived, and Batista took power easily.  This ended the rule of the constitution.

Prío was granted amnesty and returned to Cuba on August 11, 1955.  When Fidel Castro was in Mexico, Prío gave him money to support his opposition movement.  Castro used the money to purchase a boat, the Granma, which brought his rebels back into Cuba.