The city administers three villages: Bobohalma (Bábahalma), Botorca (Őrhegy), and Cuștelnic (Csüdőtelke); the last was part of Gănești Commune until 2002.

The place was historically certified in 1279, under the name of terra Dychen Sent Marton, in a document involving land relocations and ownership.

In 1502, the place was mentioned as a borough (Medieval Latin: oppidum), as a part of Cetatea de Baltă fief of the Moldavian Princes Stephen the Great and Petru Rareș.

For centuries, until the area was ceded to Romania after the Treaty of Trianon following World War I, the city was a local administrative center inside the Kingdom of Hungary and later within Austria-Hungary.

In 1936, an installation of synthetic ammonia production was set in Târnăveni, the first of this type in the world — over the following years, the company involved in the latter process switched to weapons manufacturing.

The administrative palace and the hospital were both built during the urban expansion — the latter was where the famous physician Constantin Ion Parhon, whose family was originally from Cetatea de Baltă, used to consult his patients.

[3] 230 Romanian soldiers who, after Romania parted with the Axis and joined the Allies in 1944, defended the city against German troops lie buried in the local cemetery.

A modern glassware factory — Gecsat — is situated in the southeast area, and produces a wide range of export products.

By the end of the 19th century, the Jewish population expanded, attracted to the new county capital, and played an important role in its economic development.

[5] In 1962, the local Museum of History was opened, housing separate sections for archaeology, ethnography, natural science and numismatics.