The municipalities of Vadsø, Båtsfjord, Berlevåg, Vardø, Tana, and Nesseby share the 2,069-square-kilometre (799 sq mi) peninsula.

Some parts of the paleic surface in Varanger Peninsula are a re-exposed unconformity that underlie sedimentary rock of Vendian (Late Neoproterozoic) age.

It is largely composed of Neoproterozoic to Paleozoic sedimentary rocks, locally overlying crystalline basement of the Baltic Shield.

[6] Two ancient fault systems divide the geology of the peninsula into three groups, where the NE side of the peninsula (North Varanger region) is separated from the SW by the Trollfjord-Komagelva strike-slip fault,[7] and the SW side is divided approximately NNE-SSW by thrusting of the Scandinavian Caledonides over the Baltic Shield.

[6] Notable strata of the Barents Sea Group are the Kongsfjord and Båsnæring formations, which form prominent ridges and cliffs along the Fv341 road.

[6] Strata deposited on the SW half of the Varanger Peninsula mostly formed during the mid-late Cryogenian, Ediacaran, and Paleozoic.

On the south coast, including the town of Vadsø, there is sufficient summer heat for birch trees to grow.