Almost all details of the life of Sebaldus are uncertain. However various legends about his life have been recorded.
One of the earliest legends (ca 1280) claims Sebaldus was a contemporary of Henry III (died 1056) and was of Franconian origin. After a pilgrimage in Italy, he became a preacher at Nuremberg. Another text claims that he was a Frankish nobleman who met Willibald and Winibald in Italy (thus dating his life to the 8th century) and later became a missionary in the Sebalder Reichswald that is associated with his name.