Its county seat (Romanian: reședință de județ) is the namesake town of Sibiu (German: Hermannstadt).

The south side of the county, closer to the mountains was mainly inhabited by Romanians (Mărginimea Sibiului), and the north side of the country (the Transylvanian Plateau) was inhabited evenly by Germans and Romanians, but most Saxon villages are now deserted by their original ethnic German population.

The Roma population, mainly from southern Romania, was placed close to the villages in the communist period and have since increased their numbers, especially in the Hârtibaciu valley.

Most of the population is concentrated in the Sibiu metropolitan area which has over 240 thousand inhabitants, with settlements like Șelimbăr, Cisnădie (especially the Arhitecților neighbourhood), Șura Mare, Șura Mică, Cristian, and Roșia having grown in population in the last 15 years, both from internal migration from the county and from other areas, mainly Vâlcea County.

The Olt River crosses the mountains over to the South of Romania in Sibiu County, forming one of the most accessible links between Transylvania and Wallachia.

The most important rivers crossing the county are the Olt in the South with the Cibin as its main effluent, and the Târnava in the North.