Lanfranc was born around 1005 in Pavia, Lombardy, to a noble Lombard family — the son of a magistrate of Pavia. Educated at the law-school of Pavia (the principal Italian legal centre of the early 11th century), he became a distinguished jurist before undertaking religious life.
Around 1042, crossing the Alps to teach rhetoric and law at the French cathedral schools, he was robbed and beaten by brigands on a road in Normandy — and, after miraculous deliverance, entered the obscure new Abbey of Bec (founded c. 1034 by the former soldier-knight Herluin) as a monk.
Under Lanfranc's direction, the small Abbey of Bec became one of the principal intellectual centres of the 11th-century Catholic Latin West — drawing students from across Catholic Europe to study at the Bec cathedral school. Among Lanfranc's pupils were St. Anselm of Canterbury (future Archbishop of Canterbury, successor of Lanfranc) and Pope Alexander II.
In the Berengarian Eucharistic controversy of the 1050s–1070s — when Berengar of Tours denied the substantial Eucharistic Real Presence — Lanfranc composed the principal Catholic refutation: the De Corpore et Sanguine Domini contra Berengarium Turonensem ('On the Body and Blood of the Lord against Berengar of Tours', c. 1063). The text articulated for the first time the Latin scholastic vocabulary of substantia and accidentia in Eucharistic theology — laying the direct linguistic-conceptual foundation for the doctrine of transubstantiation that would be formally defined by the Fourth Lateran Council in 1215.
In 1063 Lanfranc was appointed Abbot of the new Abbey of Saint-Étienne at Caen — the principal Norman ducal monastic foundation of Duke William of Normandy (the future William the Conqueror).
After the Norman Conquest of England in 1066, Duke William appointed Lanfranc as Archbishop of Canterbury (consecrated August 29, 1070) — succeeding the deposed Stigand, the first Norman Archbishop of England.
Lanfranc's nineteen-year archiepiscopate (1070–1089) was devoted to the Catholic ecclesiastical reorganization of the Norman-conquered Anglo-Saxon Catholic Church: reorganizing the diocesan boundaries (dioceses re-located from small rural villages to fortified Norman towns), instituting the principle of Canterbury's primacy of York (the York-Canterbury jurisdictional dispute that would persist through the medieval centuries), introducing the Norman-Cluniac liturgical and disciplinary reforms, rebuilding the Canterbury Cathedral in the Norman style after the 1067 fire (the Norman cathedral, subsequently rebuilt in the Early English Gothic style 1175–1184 by William of Sens and William the Englishman after the Becket-murder fire of 1174).
He died at Canterbury on May 24, 1089. His pupil and successor St. Anselm of Canterbury (Archbishop 1093–1109) would continue the Bec-Canterbury intellectual tradition into the High Medieval scholastic culture.