Tsivilsk, also rendered Tzivilsk or Civilsk, is a town and the administrative center of Tsivilsky District of the Chuvash Republic, Russia, located 37 kilometers (23 mi) from the republic's capital city of Cheboksary, at the crossroads of the highways from Nizhny Novgorod to Kazan and from Tsivilsk to Ulyanovsk. Population: 13,479 (2010 census); 12,967 (2002 census); 10,053 (1989 Soviet census).

The original fortress at Tsivilsk was founded in 1589 as a Russian military outpost among the Chuvash population.

Within the framework of administrative divisions, Tsivilsk serves as the administrative center of Tsivilsky District. As an administrative division, it is incorporated within Tsivilsky District as Tsivilskoye Urban Settlement. As a municipal division, this administrative unit also has urban settlement status and is a part of Tsivilsky Municipal District.

There is a 350-meter (1,150 ft) tall guyed mast used for FM- and TV-broadcasting in the town.