He was, according to his biographer in the Liber Pontificalis, the son of a man called Innocens of Albano; but according to his contemporary Jerome, his father was Pope Anastasius I (399-401), whom he was called by the unanimous voice of the clergy and laity to succeed (he had been born before his father's entry to the clergy, let alone the papacy).
It was during Innocent I's papacy that the siege of Rome by Alaric I (395-410) and the Visigoths (408) took place, when, according to an anecdote of Zosimus, the ravages of plague and famine were so frightful, and divine help seemed so far off, that papal permission was granted to sacrifice and pray to the pagan deities. The pope, however, happened to be absent from the city on a mission to Honorius at Ravenna at the time of the sack in 410.
Innocent I lost no opportunity of maintaining and extending the authority of the Roman see as the ultimate resort for the settlement of all disputes; and his still extant communications with Victricius of Rouen, Exuperius of Toulouse, Alexander of Antioch and others, as well as his actions on the appeal made to him by John Chrysostom (397-403) against Theophilus of Alexandria, show that opportunities of the kind were numerous and varied. He took a decided view on the Pelagian controversy, confirming the decisions of the synod of the province of proconsular Africa, held in Carthage in 416, which had been sent to him, and also writing in the same year in a similar sense to the fathers of the Numidian synod of Mileve who, Augustine being one of their number, had addressed him.
Among Innocent I's letters is one to Jerome and another to John, bishop of Jerusalem, regarding annoyances to which the former had been subjected by the Pelagians at Bethlehem. He died on 12 March 417. Accordingly, though from the thirteenth to the twentieth century he was commemorated on 28 July, his feast day is now 12 March. His successor was Zosimus.