As head and progenitor of the Leopoldian line, he ruled over the Inner Austrian duchies of Carinthia, Styria and Carniola as well as the County of Tyrol and Further Austria from 1379 until his death.

Nevertheless, on 18 November 1364 he promulgated his own house law (Rudolfinische Hausordnung), according to which the Austrian "hereditary lands" were again declared a common possession of the brothers, though the eldest received a number of additional rights.

On 25 July 1373 the brothers signed a peace treaty which granted Leopold control over Tirol, Further Austria and Carniola while income would be split between the dukes.

[2] In 1375 their relative Enguerrand VII de Coucy led a mercenary army into Alsace and Switzerland to capture the Habsburg possessions of Sundgau, Breisgau and the county of Ferrette in the Gugler war of 1375.

[3] When on 7 July 1379 he and Albert III signed the Treaty of Neuberg, Leopold became the exclusive ruler of Styria (then including Wiener Neustadt), Carinthia, Carniola, Tyrol and the Further Austrian lands in Swabia.