Gregory was born around 538 at Clermont in the Auvergne into a senatorial Gallo-Roman family that had already given the church several bishops on both sides, including his mother's kinsman Gregory of Langres. Educated by clerical relatives after his father's early death, he was ordained deacon and served at Lyon before returning to the Auvergne, where family connections and a reputation for piety marked him for advancement.
In 573 Gregory was elected bishop of Tours, one of Gaul's most important sees because it held the shrine of Saint Martin, the fourth century soldier turned monk whose cult drew pilgrims and royal patronage from across the Frankish kingdoms. The city sat at a dangerous crossing point between the rival Merovingian kings who had divided Clovis's inheritance, and Gregory spent much of his episcopate negotiating between them, most perilously King Chilperic of Neustria, who put him on trial for slander in 580 at the council of Berny-Riviere, after Chilperic's own wife Fredegund was accused of adultery with a Frankish bishop and Gregory was charged with having spread the claim. Gregory faced Chilperic down and kept his see.
He devoted his later years chiefly to writing, completing the Ten Books of Histories alongside works on the miracles of Martin and other saints, and he continued revising his history until close to his death in 594. He is venerated as a saint in the Catholic Church, with a feast day of 17 November, chiefly for the record he left rather than for any single act of his episcopate.