Egbert was the son of Ealhmund, King of Kent. His mother is unknown but is possibly a daughter of Ethelbert II, King of Kent.

As a young man Egbert aspired to great things, this led to his expulsion from England by Offa, King of Mercia and his son-in-law Beohrtric, King of Wessex in 789. Egbert fled to the Frankish court where Charlemagne took him in, here he meet his wife Raedburh, or Redburga, who was a daughter of Charlemagne's sister-in law.

On his return to England, Egbert peacefully ascended the throne. The Anglo-Saxon chronicle states in 802 that 'King Beohrtric passed away... and Egbert succeeded to the Kingdom of Wessex'. Nothing much of interest seems to have happened for the next 20 years, which is strange for the times but in 825 Egbert fought a battle at Ellendun, Wiltshire against Beornwulf, King of Mercia. He was victorious in what is recorded as a very bloody battle.

After this victory Egbert sent his son Ethelwulf into battle in Kent. He succeeded in driving King Baldred north of the Thames and soon Kent, Surrey, Sussex, Essex, East Anglia had turned to Egbert to be their guardian and protector from the Mercians.

Beornwolf was slain by the East Angles to be followed quickly by two other Kings until in 829 Egbert conquered Mercia and thus everything south of the Humber, becoming the 8th Bretwalda or ruler of Britain. He spent his final years fighting the Danes as his successors would do, the Danes had allies in the Cornish but Egbert saw them off at Hingston Down. He died in 839 and is buried at Winchester. His elder son Ethelwulf suceeded him, the younger Athelstan became sub-king in Kent, Essex, Sussex and Surrey.