Plegmund was born around 840 in Cheshire, Mercia (the Anglo-Saxon Catholic Mercian kingdom). He spent his early ecclesiastical life as a hermit on a small island in the river Gowy near Chester — the site that still bears his name as Plemstall ('Plegmund's stall/hermitage').
Recognized by King Alfred the Great for his learning, he was summoned to the royal court at Winchester and became one of the principal scholars of the Alfredian renaissance — the late-9th-century revival of Anglo-Saxon Catholic learning that Alfred had launched in response to the devastation of the Viking onslaught (the famous lament of Alfred's preface to the Pastoral Care: 'so completely fallen away in England, that there were very few on this side of the Humber who could understand their service-books in English').
Plegmund was one of the principal collaborators on Alfred's Old English translation programme — assisting in the translation of Latin theological texts (Gregory the Great's Pastoral Care, Boethius's Consolation of Philosophy) into Old English for the instruction of the Anglo-Saxon priesthood.
In 890 Alfred appointed him Archbishop of Canterbury — succeeding Æthelred. He travelled to Rome to receive the pallium (the symbol of metropolitan archiepiscopal authority) from Pope Formosus in 891, and again to Rome in 908 under Pope Sergius III. He crowned Alfred's son Edward the Elder as king of the Anglo-Saxons in 899.
He established the five new dioceses of Wessex in 909 (Wells, Crediton, Ramsbury, Sherborne, Selsey) — reorganizing the southern English Catholic diocesan structure for the expanding Wessex Catholic kingdom. He died on August 2, 914 at Canterbury, having served as Archbishop for 24 years through the reigns of Alfred and Edward the Elder.

