Francis was born in Southern Italy, in the town of Grottaglie, in southern Italy, near Taranto. When He was ten years old, Francis was sent to live with the Theatine priests, serving as sacristan in exchange for board and room. He also accompanied some of the priests on their missions to neighboring towns. In 1658 he received the tonsure, and one year later, at the recommendation of the Theatines, he began studying at the Jesuit school in Taranto.
When Francis was twenty-three, he attended the Jesuit's college in Naples, and one year later, on March 20, 1666, he was ordained a priest. His first years after ordination were spent acting as prefect of studies for the sons of noble families in Naples. He entered the Jesuit novitiate on July 1, 1670, and one year later was sent to the diocese of Lecce to assist in the retreat ministry there. For the next three years Francis preached throughout Southern Italy.
Having passed the final examinations in theology in 1676, he was assigned to the missions in and around Naples. His ministerial activities were varied: Every Sunday, he preached in the city square and offered Mass there; he also preached to the sodality of local artisans. Every Monday and Saturday he preached in the streets of Naples and took this mission to the suburbs on Tuesdays and Fridays. In addition to visiting slaves, prisoners and criminals in the galleys, he preached in the bad sections of the city. He also formed a sodality of artisans, who were considered his "protégés." To these various audiences Francis' usual theme was God's forgiveness.
At one point in his ministry, Francis wrote to the Father General asking to be sent to India or Japan. The General responded: "The Kingdom of Naples is to be your Indies and Japan."
The period 1688-1694 was marked by humiliation and contradiction for Francis. He was no longer allowed to preach in the streets because some powerful citizens had objected to the Archbishop, so Francis spent his time hearing confessions in the Jesuit Church. The Archbishop later learned that the complaints against Francis were unfounded, and the prelate both apologized and reinstated the Jesuit preacher.
Another humiliation was caused by his own brethren, who complained to the Jesuit provincial that because of his work in the city, Francis did not attend all community functions. As a result, Francis had to ask permission for any work outside of the Jesuit house in Naples. The ban lasted for ten years; only in 1704, did Francis resume his work throughout the city.
For the next twelve years, Francis labored half of the year in Naples; the other six months were given to itinerant preaching. His sermons were described as "simple," "earnest," and "classical." His preaching was occasionally accompanied by prophesying and healing.
Father de Geronimo's final mission took place in 1715. Suffering from pleurisy, he gave his final sermon on March 1716. He was anointed on May 9, and died on May 11, 1716.
Francis de Geronimo was beatified in 1806, and canonized on May 26, 1839 by Pope Gregory XVI