Croatia-Slavonia was an autonomous kingdom within the Lands of the Crown of Saint Stephen (Transleithania), the Hungarian part of the dual Austro-Hungarian Empire.

The capital of the county was Zagreb (Croatian, in Hungarian: Zágráb).

The territory of the Zagreb County was part of the Kingdom of Croatia when it entered a personal union with the Kingdom of Hungary in 1102, and with it became part of the Habsburg monarchy in 1526.

Zagreb County was re-established after it was liberated from Ottoman occupation in the early 18th century.

[citation needed] In 1920, by the Treaty of Trianon the county became part of the newly formed Kingdom of Serbs, Croats and Slovenes (later renamed to Yugoslavia).