His ancestry is thus given by the "Anglo-Saxon Chronicle": "Ceolwulf was the son of Cutha, Cutha of Cuthwin, Cuthwin of Leoldwald, Leoldwald of Egwald, Egwald of Aldhelm, Aldhelm of Ocga, Ocga of Ida, Ida of Eoppa." Ceolwulf's brother, Coenred, seized the Northumbrian throne in AD 716. Coenred ruled for two years when Osric, the last of the House of Aethelric, claimed the throne and ruled for ten years. In 729, shortly before his death, Osric nominated Ceolwulf as his successor.
Ceolwulf was a man with deep monastic interests, and perhaps little suited to affairs of state. Bede dedicated his Historia ecclesiastica gentis Anglorum ("History of the English Church") to Ceolwulf in 731. That same year Ceolwulf was deposed for a short period in the autumn of 731 or 732, but quickly restored. The details of the attempted coup are unclear. Bishop Acca of Hexham is said to have been deprived of his see.
It has been suggested that Ceolwulf had spent time in Ireland, perhaps studying to enter into religion. As King, he had endowed the monastery at Lindifarne with many gifts. He obtained a dispensation for the monks to use of wine and beer for the monks, contrary to the established Celtic practice which limited beverages to water and milk.
In 737 Ceolwulf abdicated in favor of his first cousin Eadberht, to retire to Lindisfarne. His death is recorded in the winter of 764–765. He was later canonized, and his feast day is January 15.