Rudolf was the eldest son of Duke Albert I of Austria and his wife Elizabeth of Gorizia-Tyrol, thereby the grandson of King Rudolf I of Germany. After lengthy struggles with Adolf of Nassau, his father was elected King of Germany in 1298 and vested sixteen-year-old Rudolf as a co-ruler with the Austrian hereditary lands of the Habsburg dynasty. According to the Treaty of Rheinfelden, Rudolf acted as regent on behalf of his younger brothers Frederick the Fair and Leopold I.
