Hermagor is located in the lower Gail valley at the northern foot of the Carnic Alps, close to the border with Italy.

In the north, the road leads via Gitschtal into the Gailtal Alps, across Kreuzberg Saddle to the Weissensee lake and further down to Greifenburg in the Drava valley.

Hermagor-Pressegger See is divided into the following cadastral communities: It is further divided into the following settlements: Achleiten (4), Aigen (4), Bergl (24), Braunitzen (12) (Boronica), Brugg (31) (Moste), Burgstall (9), Danz (26), Dellach (94) (Dole), Egg (178) (Brdo), Eggforst (10), Förolach (162), Fritzendorf (58) (Limarče), Görtschach (173), Götzing (22) (Gocina), Grafenau (0) (Kazla), Grünburg (70), Guggenberg (34), Hermagor (1.527) (Šmohor), Jenig (178) (Jenik), Kameritsch (80) (Kamerče), Khünburg (247), Kleinbergl (30), Kraß (14), Kraschach (57) (Krošani), Kreuth ob Möschach (19) (Rut(e)), Kreuth ob Mellweg (60) (Rut(e)), Kreuth ob Rattendorf (76) (Rute(e)), Kühweg (202), Kühwegboden (156), Latschach (86) (Loče), Liesch (7), Möderndorf (223) (Modrinja vas/ves), Mellach (49) (Mele), Mellweg (45) (Melviče, Maloviše), Micheldorf (167) (Velika vas/ves), Mitschig (79) (Mičiče), Nampolach (27) (Napole), Neudorf (271), Neuprießenegg (36), Obermöschach (38), Obervellach (243), Paßriach (143)(Pažirje), Podlanig (51) (Podlanig), Postran (123) (Postran), Potschach (61) (Potoče), Presseggen (222) (Preseka), Presseggersee (130) (Preseško jezero), Radnig (203), Radnigforst (0), Rattendorf (343) (Radnja vas), Schinzengraben (26), Schlanitzen (41) (Zelenica), Schmidt (1), Siebenbrünn (2), Sonnenalpe Naßfeld (27)(Mokrine), Sonnleitn (17), Süßenberg (20) (Planja), Toschehof (0) (Tesinje), Tröpolach (535) (Dobropolje, Dropolje), Untermöschach (48), Untervellach (229), Watschig (129) (Vočiče), Wittenig (50), Zuchen (3) (Suha).

Due to its strategic location, it quickly prospered, obtained market rights in 1288, and became the main settlement of the Gail valley.

The Gailtal Railway line was built from 1894, it was extended in 1915 for military purposes on the Italian Front of World War I. Hermagor obtained town privileges on 10 October 1930, on the occasion of the tenth anniversary of the Carinthian plebiscite.