Abrupt climate events profoundly impact human societies, both environmentally and socially. However, existing research predominantly concentrates on immediate responses, overlooking long-term consequences. This study, centered on the Guojiazaoyuan site in the southern Loess Plateau, explores the enduring effects of a 5.3-ka BP climate event that transformed the local subsistence system. Through detailed analysis of archaeobotanical evidence, specifically floral remains dating to 4800–4300 BP obtained via flotation, significant post-event shifts in agricultural practices and food strategies are revealed. Notably, there is a clear prioritization of foxtail millet cultivation, a shift towards diversified food sources, and the introduction of new livestock. These changes represent strategic adaptations aimed at bolstering resilience and reducing vulnerability to future climatic challenges. The southern Loess Plateau developed an agricultural pattern with foxtail millet as the dominant crop, although different patterns were observed in surrounding regions during the early Longshan period (4800–4300 BP). Emphasizing the importance of a long-term perspective, particularly in agriculture and food security, the findings contribute to a broader understanding of how ancient societies coped with environmental changes. These insights are pertinent to ongoing discussions on climate resilience and sustainable agriculture.