Leodegrance had served Uther Pendragon, King Arthur's biological father and regnal predecessor. Leodegrance was entrusted with the keeping of the Round Table at Uther's death. When Guinevere marries Arthur, Leodegrance gives the young king the table as a wedding present. In later romance Leodegrance is one of the few kings who accept Arthur as his overlord. For this, his land is invaded by the rebel King Rience, but Arthur comes to his rescue and expels the enemy. Arthur meets Guinevere for the first time during this excursion, and they develop a love that eventually results in their fateful marriage.
According to the Lancelot–Grail Cycle, Leodegrance fathered a second daughter out of wedlock; he also names this child Guinevere. The "False Guinevere" later treacherously convinces Arthur's court that she is his real wife and her sister is an impostor, forcing the real queen and her lover Lancelot into hiding with their friend Galehaut. Guinevere eventually returns and reclaims her throne.