A county seat is an administrative center, seat of government, or capital city of a county or civil parish. The term is in use in six countries: Canada, China, Hungary, Romania, Taiwan, and the United States. An equivalent term, shire town, is used in the U.S. state of Vermont and in several other English-speaking jurisdictions.

In Canada, the provinces of Ontario, Quebec, New Brunswick, Prince Edward Island, and Nova Scotia have counties as an administrative division of government below the provincial level, and thus county seats. In the provinces of Prince Edward Island, New Brunswick, and Nova Scotia, the term "shire town" is used in place of county seat.

County seats in China are the administrative centers of the counties in the People's Republic of China. They have existed since the Warring States period and were set up nationwide by the Qin dynasty. The number of counties in China proper gradually increased from dynasty to dynasty. As Qin Shi Huang reorganized the counties after his unification, there were about 1,000. Under the Eastern Han dynasty, the number of counties increased to above 1,000. About 1400 existed when the Sui dynasty abolished the commandery level (郡 jùn), which was the level just above counties, and demoted some commanderies to counties.

In Imperial China, the county was a significant administrative unit because it marked the lowest level of the imperial bureaucratic structure; in other words, it was the lowest level that the government reached. Government below the county level was often undertaken through informal non-bureaucratic means, varying between dynasties. The head of a county was the magistrate, who oversaw both the day-to-day operations of the county as well as civil and criminal cases.

The current number of counties mostly resembled that of the later years of the Qing dynasty. Changes of location and names of counties in Chinese history have been a major field of research in Chinese historical geography, especially from the 1960s to the 1980s. There are 1,355 counties in Mainland China out of a total of 2,851 county-level divisions.

In Taiwan, the first counties were first established in 1661 by the Kingdom of Tungning. The later ruler Qing empire inherited this type of administrative divisions. With the increase of Han Chinese population in Taiwan, the number of counties also grew by time. By the end of Qing era, there were 11 counties in Taiwan. Protestant missionaries in China first romanized the term as hien. When Taiwan became a Japanese colony in 1895, the hierarchy of divisions also incorporated into the Japanese system in the period when Taiwan was under Japanese rule.

By September 1945, Taiwan was divided into 8 prefectures (州 and 廳), which remained after the Republic of China took over.

There are 13 county seats in Taiwan, which function as county-administered cities, urban townships, or rural townships.