In 1533, Philip moved to San Germano to help some family with their business, and while there would escape to a local Dominican chapel in the mountains. He received word in a vision that he had an apostolate in Rome. So, he cut himself off from his family and went there. Philip was befriended by Galeotto Caccia who took him in, and paid him to tutor his two sons. Philip wrote poetry in Latin and Italian, and as well, he studied philosophy and theology. When he tired of learning, he sold all his books and gave the money to the poor.
Philip began to visit and care for the sick and impoverished pilgrims. He founded a society of like-minded folk to do the same. He was a friend of Saint Ignatius Loyola. A layman, he lived in the city as a hermit. During Easter season of 1544, while praying in the catacomb of San Sebastiano, he received a vision of a globe of fire that entered his chest, and he experienced an ecstasy that physically enlarged his heart.
With Persiano Rose, he founded the Confraternity of the Most Holy Trinity. He began to preach, with many converts. In 1550, he considered retiring to the life of a solitary hermit, but received further visions that told him his mission was in Rome. Later he considered missionary work in India, but further visions convinced him to stay in Rome.
Philip entered the priesthood in 1551, where he heard confessions by the hour. He could tell penitents their sins before they confessed, and had the gift of conferring visions. He began working with youth, finding safe places for them to play, and becoming involved in their lives. Pope Gregory XIII tried to make him a cardinal, but Philip declined. He founded the Congregation of the Oratory, approval being granted by Pope Gregory XIII in 1575. It spread rapidly through Italy and Philip was elected superior general. His life was remarkable for his singular devotion to the Blessed Sacrament. In later years, he was beset by several illnesses, each of which was in turn cured through prayer.
Saint Philip Neri died of natural causes on May 27, 1595 at Rome, Italy. His body is at a shrine in Chiesa Nuova.