["International Journal of Osteoarchaeology, EarlyView. ", "\nABSTRACT\nA complex hunter–gatherer culture among affluent, sedentary communities had persisted across South China until the arrival of rice farmers after 5000 bp. Previous studies have shown that these complex hunter–gatherer groups had extensive exploitation of wild plants, terrestrial animals, and freshwater resources. However, there has been limited direct evidence of potential changes in the exploitation of these resources over time. Here, we apply stable carbon and nitrogen isotope analyses and AMS‐14C dating to human and animal bones from two open‐air sites in Western Guangxi, Kantun, and Baida, and integrate published isotopic data from Northern (Zengpiyan and Dayan cave sites) and Southern Guangxi (Dingsishan shell midden site), using Bayesian modeling to reconstruct prehistoric diets and subsistence change. The results demonstrate that prehistoric populations in Guangxi intensified their exploitation of C3 plant resources from the Early to Middle Neolithic periods. We argue that our data provide new evidence on the early subsistence changes across diverse geographical regions and site types in South China and offer new insights into discussions on environmental adaptations of prehistoric hunter–gatherers.\n"]