The southern third, predominantly Slovene-speaking Lower Styria, became part of the Kingdom of Serbs, Croats and Slovenes (Yugoslavia) after World War I.

In the Middle Ages, the Lower Styrian lands were ruled by several immediate (reichsfrei) dynasties like the Counts of Celje, whose large possessions were not incorporated by the Habsburg dukes until the 15th century.

In early November 1918, Rudolf Maister, a Slovene major of the former Austro-Hungarian Army, with about 4,000 local volunteers occupied Lower Styria and the town of Maribor and claimed it for Yugoslavia.

After a short fight with German-Austrian paramilitary units, the current border was established, acknowledged by the provisional Styrian assembly at Graz.

[4] Confirmed by the 1919 Treaty of Saint-Germain-en-Laye, the border between Yugoslav and Austrian Styria mostly followed the ethnic-linguistic dividing line between Slovenes and ethnic Germans.

[7] Following the reorganization implemented by the Yugoslav constitution of 1931, Slovene Styria was incorporated in the newly established Drava Banovina, which was more or less identical with Slovenia, with Ljubljana as its capital city.

After World War II, Yugoslav authority over the region was established and Slovene Styria became an integral part of the Socialist Republic of Slovenia.

According to prior decisions made by the Anti-Fascist Council of the People's Liberation of Yugoslavia, an expulsion of the remaining ethnic German population was carried out, regardless of their links to the Nazi regime.

Styria is known for its white wine, especially Ljutomer Riesling, for the Pohorje ski resort, for cultural festivals and for pumpkin seed oil.