We present the results of a diachronic survey of the Katsaronio plain in the Karystia, southern Euboea, Greece. The project was organized under the aegis of the Norwegian Institute at Athens with a permit from the Hellenic Ministry of Culture under the official name of the Norwegian Archaeological Survey in the Karystia. Five years of fieldwork (2012–16) covered an area of 20 km2 in a large agricultural plain located about 5 km north-west of the town of Karystos. The survey identified 99 new findspots with a range of dates spanning from the Final Neolithic to Early Modern times. Here we present the collected prehistoric through Roman data, which represent the bulk of the acquired evidence. One of the notable features of the assemblage is the vast quantity of lithics that were recovered, numbering over 9,000 and consisting mainly of obsidian. Certain periods were absent from the evidence, such as post-Early Bronze Age prehistoric and Geometric, while others were represented with varying intensity. We offer initial interpretation of the patterns observable in the evidence in an attempt to reconstruct the past use and habitation of this part of Euboea.