Jirkov (Czech pronunciation: [ˈjɪrkof]; German: Görkau) is a town in Chomutov District in the Ústí nad Labem Region of the Czech Republic. It has about 19,000 inhabitants. Jirkov creates a conurbation with Chomutov.

Jirkov consists of five municipal parts (in brackets population according to the 2021 census):

The name is derived from the personal name Jirek (a diminutive of Jiří), meaning "Jirek's (court)". The personal name was initially written as Jurek and the settlement's name as Jurkov.

Jirkov lies in close proximity to the city of Chomutov, with which it forms a conurbation. It is located about 44 km (27 mi) southwest of Ústí nad Labem. It lies on the border between the Most Basin and Ore Mountains. The highest point is at 590 m (1,940 ft) above sea level.The Bílina River flows through the town.

Jirkov was established as a colonization village on the Czech-Saxon border in the second half of the 13th century. The first written mention of Jirkov is from 1321 under the name Borek, the name Jirkov (that time written Jurkov) began to be used soon after.

From 1938 to 1945, Jirkov was annexed by Nazi Germany and administered as part of the Reichsgau Sudetenland. After the surrender of Germany, nearly all of the town's hitherto inhabitants were expelled, and new Czech settlers found a new home in the depopulated town.

Jirkov is the terminus and starting point of the railway line from/to Lužná via Chomutov.

Jirkov and neighbouring Chomutov together operate a transport company. In addition to buses, public transport is provided also by trolleybuses.