We describe Carex socotrana Rěpka & Maděra, a new endemic species found in the Hajhir Mountains on Socotra Island. It differs from the morphologically similar African continental species C. steudneri Boeckeler in having a shorter stem, smaller leaf length and width, completely smooth leaf blades and margins, and pistillate scales without a whitish membranous margin and with distinctive awns at the apex. The spike clusters are smaller and more scattered on the stem, and the perigynium and its beak are smaller than in C. steudneri. So far only one small and one large population have been found near the highest mountain peak, Mount Scand. The new taxon is 1370 km from the closest known site of C. steudneri.