He confronted Navarre and Castile, who supported his half-brother Sancho the Fat in disputing Ordoño's claim to the throne.

In response to the Muslims, Ordoño III led a raid as far as Lisbon (955), coming back north with a very lucrative haul of loot.

[1] Faced with this great show of force, Abd-al-Rahman III (912–961) was pushed to negotiate and conclude a peace treaty with the king of León.

He tried to continue the actions of his father in fortifying the land and the royal authority in the face of the wilfully secessional Fernán González of Castile.

Ordoño III was also father of Bermudo II, but opinion is divided as to whether he was son of Urraca, or of a mistress, one of the daughters of Count Pelayo González.