Taichung County was established on 26 November 1945 on the territory of Taichū Prefecture (臺中州) shortly after the end of World War II.

The remaining Taichung County has territory equivalent to the Toyohara (Fengyüan), Tōsei (Tungshih), Taikō (Tachia), and Daiton (Tatun) in the Japanese era.

In addition, districts in the remaining part of Taichung County was defunct.

On 25 December 2010, the county merged with Taichung City to form a larger single special municipality.

On the eve of merging with Taichung City, the county consists of the following administrative divisions