Through the patronage of Ginés Rabaza Perellós, Marquis of Dos Aquas, he enrolled at the University of Valencia in 1721. In 1724, he began the study of Christian theology at the University of Valencia, receiving a master"s degree after three years. He taught Thomistic philosophy from 1728 to 1735.
In 1735, he became professor of Thomistic philosophy, holding that chair until it was abolished in 1738.
In 1739, again through the patronage of Ginés Rabaza Perellós, Marquis of Dos Aquas, he was appointed parish priest of Bétera. He became parish priest of Massamagrell in 1752.
In 1759, he became a canon of Valencia Cathedral. He was appointed Bishop of Salamanca on July 18, 1763, and he was consecrated as a bishop on September 25, 1763.
He was a supporter of the expulsion of the Jesuits from Spain in 1767.
He was appointed Grand Inquisitor of Spain on December 24, 1774. As Grand Inquisitor, he continued the suppression of Jansenism in Spain. He oversaw the heresy trial of Pablo de Olavide in 1775.
He acted as patron of Pedro Estala.
José Francisco de Isla wrote satire directed at Beltrán. Beltrán received the Order of Charles III in 1780.
He died on December 1, 1783.