A minor upon his father's death on a crusade in 1164, Ottokar IV was raised under the tutelage of his mother Kunigunde and Styrian ministeriales.

Backed by his maternal uncle Emperor Frederick Barbarossa, he made great efforts to secure the Imperial border against the Kingdom of Hungary in the east; he had his Graz residence rebuilt and the fortress of Fürstenfeld erected about 1170.

Childless and deathly ill, Ottokar IV, who had contracted leprosy while on crusade, was the first but also the last duke of the Otakars.

With the consent of the emperor, he entered into the Georgenberg Pact with Duke Leopold V of Austria in 1186: both dukes met in Enns and agreed that Ottokar was to give his duchy to Leopold and to his son Frederick, under the stipulation that Austria and Styria would henceforth remain undivided.

The inheritance contract brought Styria under joint rule with the Duchy of Austria after Ottokar's death in 1192.