Cities and towns are marked in bold and market towns in italics: Bílence - Blatno - Boleboř - Březno - Černovice - Chbany - Chomutov - Domašín - Droužkovice - Hora Svatého Šebestiána - Hrušovany - Jirkov - Kadaň - Kalek - Klášterec nad Ohří - Kovářská - Křimov - Kryštofovy Hamry - Libědice - Loučná pod Klínovcem - Málkov - Mašťov - Měděnec - Místo - Nezabylice - Okounov - Otvice - Perštejn - Pesvice - Pětipsy - Račetice - Radonice - Rokle - Spořice - Strupčice - Údlice - Vejprty - Veliká Ves - Vilémov - Vrskmaň - Všehrdy - Všestudy - Výsluní - Vysoká Pec Chomutov District borders Germany in the north.

The highest point of the district and the entire Ústí nad Labem Region is a contour line below the top of the Klínovec Mountain in Loučná pod Klínovcem with an elevation of 1,231 metres (4,039 ft), the highest peak is the nearby Macecha at 1,113 m (3,652 ft).

The lowest point is the river bed of the Ohře in Březno at 220 m (720 ft).

Notable are the rivers Bílina and Chomutovka that originates here and drain the northern part.

Mědník Hill in Měděnec was designated a UNESCO World Heritage Site in 2019 as part of the transnational Ore Mountain Mining Region.