Komárom-Esztergom (Hungarian: Komárom-Esztergom vármegye, pronounced [ˈkomaːrom ˈɛstɛrɡom]; German: Burgkomitat Komorn-Gran; Slovak: Komárňansko-ostrihomská župa) is an administrative Hungarian county in Central Transdanubia Region; its shares its northern border the Danube with Slovakia.

Throughout their history the borders of the two counties were frequently modified, and they were merged several times as well.

During the Ottoman occupation of Hungary, Esztergom became the center of a sanjak spanning across several counties.

Komárom county on the other hand was continuously functioning, its castle was never captured by the conquering armies.

The general assembly of nobles in Esztergom county was reintroduced after the liberation of the city from the Ottomans, by armies led by John III Sobieski in 1696.

In January 1919 the Czechoslovak Legion occupied the towns of Párkány and Komárom on the northern bank of the Danube.

As a consequence of the temporary armistice following World War II the 1937 borders of the country were restored.

48,000 persons in Komárom-Esztergom County did not declare an ethnic group at the 2011 census.