Otto followed his father, Henry I, as king of Germany in 936. Otto dealt successfully with several revolts of his family members, of the Slavs in Poland and Bohemia, and most of all with the incursions of the raiding Magyars. He crushed the Magyars decisively at the battle of Lechfield in Swabia.

In 961, Otto crossed the Alps to put down an anti-papal uprising in Rome. For this service, Otto was crowned Holy Roman emperor.