Seaxburh's sisters were Æthelburg of Faremoutiers, Saethryth, Æthelthryth and possibly Withburga. Her marriage to Eorcenberht produced two sons, both of whom ruled, and two daughters. After her husband's death in 664, Seaxburh remained in Kent to bring up her children. She acted as regent until her young son Ecgberht came of age.