Sæbbi was son of Sexred and was the joint King of Essex from 664 to about 683 along with his cousin, Sighere. After Sighere died, Sæbbi became sole ruler of Essex until 694.

The Kingdom of the East Saxons, referred to as the Kingdom of Essex, was one of the seven traditional kingdoms of the Anglo-Saxon Heptarchy. It was founded in the 6th century and covered the territory later occupied by the counties of Essex, Middlesex, much of Hertfordshire and west Kent. The last king of Essex was Sigered of Essex, who in 825 ceded the kingdom to Ecgberht, King of Wessex. From 825 Essex was ruled as part of a south-eastern kingdom of Essex, Kent, Sussex and Surrey. It was not until 860 that Essex was fully integrated into the crown of Wessex.