Berno was born about the year 850 to a noble family in Burgundy. His father may have been the French nobleman Odon, who gave a refuge for the Benedictine community from Glanfeuil Abbey after the monks had been driven from the monastery by Norman attacks in 862. Berno joined the Benedictine Abbey of St. Martin at Autun, where Hugh of Anzy le Duc had introduced stricter adherence to the Rule of Saint Benedict. Later, Berno was sent to restore the monastery of Baume-les-Messieurs in the diocese of Besançon, which had fallen into neglect.