Koufonisia (Greek: Κουφονήσια) is a former community in the Cyclades, Greece. Since the 2011 local government reform it is part of the municipality Naxos and Lesser Cyclades, of which it is a municipal unit. It consists of three main islands.
Koufonisia consists of three main islands, Kato (Lower) and Pano (Upper) Koufonisi, and Keros, that belong to the complex of Small East Cyclades. Geographically, it is located on the southeast side of Naxos and on the west side of Amorgos. Uninhabited Keros is a protected archaeological site from which a large number of ancient Cycladic art pieces have been excavated in the 20th century.