Born at Thorens, in the Duchy of Savoy, his father, Francois de Sales de Boisy, and his mother, Francoise de Sionnaz, belonged to old Savoyard aristocratic families. His father intended him for the magistracy. He studied rhetoric and humanities at the college of Clermont, Paris, under the care of the Jesuits. There he began a course of theology and suffered a severe bout of depression from which he was suddenly freed as he knelt before an image of the Virgin Mary. In 1588 he studied law at Padua, and received his doctorate in 1592. Having qualified as a lawyer, he was about to be appointed senator. His father had selected one of the noblest heiresses of Savoy for his wife, but to his father's annoyance, Francis announced his intention to pursue a religious career. He was appointed Provost of the Chapter of Geneva, a post in the patronage of the pope. His father relented and Francis received Holy Orders (1593).
At Annecy, the new provost devoted himself to his ministry. In the following year (1594) he volunteered to convert Le Chablais, where the Genevans had adopted Calvinism and rejected the Catholic church. Risking his life, he journeyed through the entire district, preaching constantly. and at last succeeded in converting several leading Calvinists. He almost succeeded with Theodore Beza, who was called the Patriarch of the Reformation.
Pope Clement VIII sent him to Paris where he impressed the French King Henry IV. In 1602 Francis became Bishop of Geneva, a centre of resistance to the Catholic church. (1602). He became renowned for his goodness, patience and mildness and showed an intense love for the poor. He abandoned luxury and expense, in order to be able to provide for the wants of the needy. Together with St. Jane Frances de Chantal, he founded (1607) the Institute of the Visitation of the Blessed Virgin, for young girls and widows who felt themselves called to the religious life. He became renowned in Europe for his preaching.
In 1622 he had to accompany the Court of Savoy into France. At Lyons he insisted on occupying a small, poorly furnished room in a house belonging to the gardener of the Convent. There, on 27 December, he suffered a stroke and aged 56. His body was brought back to Annecy, but his heart was left at Lyons. Many miracles were reported by pilgrims to his tomb. At the time of the French Revolution, his heart was taken for safety by nuns from Lyons to Venice, where it is venerated to-day. St. Francis de Sales was canonized by Pope Alexander VII in 1665.