From the time of the duchy's establishment, it was located in the southeastern periphery of the Holy Roman Empire, where the Gorjanci Mountains and the Kolpa River formed the border with the Kingdom of Croatia.

In the northeast and east, it bordered on the Duchy of Styria, i.e., the present-day Štajerska or Lower Styrian lands beyond the Sava River, which until 1456 were held by the Counts of Celje.

In the west, the peaks of the Julian Alps high above Lake Bohinj marked the border with the historic Friulian region, initially held by the Patriarchs of Aquileia, but gradually conquered by the Republic of Venice and incorporated into the Domini di Terraferma by 1433.

In the southwest, beyond the Dinaric Alps, the Counts of Görz held the remaining Friulian territory, which in 1754 became the Austrian crown land of Gorizia and Gradisca (part of the present-day Slovenian Littoral).

Between 1861 and 1918, Carniola was divided into eleven districts consisting of 359 municipalities (German: Ortsgemeinde, Slovene: občina), with the provincial capital serving as the residence of the imperial governor (Landeshauptmann).

Albert's son Rudolf IV of Austria, "the Founder", in the course of his Privilegium Maius, awarded himself the title of a "Duke of Carniola" in 1364—though without consent by the Holy Roman Emperor.

With the Treaty of Schönbrunn in 1809, Napoleon formed the short-lived Illyrian Provinces from the annexed territories in Carniola, Carinthia, Croatia, Gorizia and Gradisca, and Trieste.

After the disestablishment of the Illyrian Kingdom in 1849, the Duchy of Carniola was constituted by rescript of 20 December 1860, and by imperial patent of 26 February 1861 (February Patent), modified by legislation of 21 December 1867, granting power to the Carniolan Landtag (or Carniolan Diet - estates' assembly) to enact all laws not reserved to the Imperial Council in Vienna, at which it was represented by eleven delegates, of whom two elected by the landowners, three by the cities, towns, commercial and industrial boards, five by the village communes, and one by a fifth curia by secret ballot, every duly registered male twenty-four years of age had the right to vote.

The business of the chamber was restricted to legislating on agriculture, public and charitable institutions, administration of communes, church and school affairs, the transportation and housing of soldiers in war and during manoeuvres, and other local matters.

In 1463 Emperor Frederick III, having prevailed against the claims raised by his brother Albert VI of Austria, added the Imperial crown to the eagle and replaced the white in the shield and the checkered crescent with gold.

Under the Habsburg rule the white, blue and red from the Carniolan coat of arms (the shield, the eagle and the crescent) were confirmed as the official flag colors of the crownland in 1848.

The Slovenian coat of arms is also a heraldic composite, incorporating the stars of the counts of Celje, the Carniolan colors and the silhouette of the Slovene national symbol, Mount Triglav.