After World War I and the break-up of empires, the Soviet Hungarian Republic came to power in 1919, followed quickly by the Kingdom of Hungary. Komárom-Esztergom was created from the ethnic Hungarian parts of the pre-1918 counties Komárom and Esztergom, formerly part of the Austro-Hungarian Empire.
The pre-1918 situation was temporarily restored during World War II. Between World War II and about 1990, during the Communist regime, the county was called Komárom. Since the establishment of Hungary, it was named Komárom-Esztergom to refer to its historic past.
The county is ranked second in terms of population density among counties in Hungary: 66% of people live in towns.