The territory traditionally inhabited by the Lemkos forms an ethnographic peninsula 140 km long and 25–50 km wide within Polish and Slovak territory. A small part of the Lemko region extends into the territory of Ukraine. After the deportation of Lemkos from the northern part in 1946, only the southern part, southwest of the Carpathian Mountains, known as the Prešov (Priashiv) region in Slovakia, has remained inhabited by Lemkos.

The Lemko region occupies the lowest part of the Ukrainian Carpathians—most of the Low Beskyd, the western part of the Middle Beskyd, and the eastern fringe of the Western Beskyd. The landscape is mountainous terrain, with ridges reaching 1,000 m and sometimes 1,300 m. Only small parts of southern Low Beskyd and the northern Sian region have a low-mountain landscape.

The northern border with the Poles runs along the first mountain ridges, which closed off the Ukrainian ethnic territory from the low foothills populated densely by the Poles . Toward the east the Ukrainian-Polish border descends from the highlands and runs across the foothills and the Sianik Depression, which is an ethnically mixed zone.

The southern, Slovak limit of the Lemko region has many ethnic islands and peninsulas: the Slovaks expanded far north along the wide valleys, whereas the Lemkos generally inhabited the mountains.

The eastern border with other Ukrainian ethnic groups consists of a wide Lemko–Boiko transitional belt from the Oslava River to the Solynka River.

Until 1946 the Galician* Lemko region comprised the southern part of Nowy Sącz, Gorlice, Jasło, Krosno, and Sianik counties, the southwestern part of Lisko county, and four villages of Nowy Targ county. Altogether the area covered nearly 3,500 sq km and had a population of 200,000, of which 160,000 (1939) were Ukrainians inhabiting about 300 villages. North of the homogeneous Lemko region lie one large and a few small islands of zamishantsi, whose dialect is close to the Lemko dialect.

The Transcarpathian Lemko region occupies most of the Prešov (Priashiv) region—about 3,000 square km with a population of 110,000 and a series of ethnic islands.

(*Galicia was a political entity comprised of Polish and Ukrainian counties)