Climate-related disturbances are increasingly identified as major determinants of food insecurity in fragile environments, yet empirical evidence remains scarce in conflict-affected areas such as the eastern Democratic Republic of Congo (DRC). Using high-frequency FAO DIEM-Monitoring surveys (2022–2026), this paper estimates the causal effect of climate shocks on household food security in the provinces of Ituri, North Kivu, South Kivu, and Tanganyika. Food security is measured with five validated indicators (FCS, HDDS, HHS, FIES, and rCSI); capturing multiple dimensions of access, consumption, and coping. To address endogeneity in self-reported shock exposure, the authors apply an instrumental-variable Conditional Mixed Process (IV-CMP) model and triangulate results with a pseudo-panel fixed-effects ordered probit model based on FIES severity. Objective climate proxies (rainfall and NDVI) are used to reinforce robustness. The results indicate that climate shocks lead to a significant deterioration in food consumption and raise the likelihood of households experiencing both moderate and severe food insecurity, thereby undermining sustainable food security. Effects are heterogeneous across provinces, reflecting the interaction between climate variability, conflict intensity, and market access constraints. Female-headed households are disproportionately affected in some areas, highlighting gendered vulnerabilities, while income, education, livestock ownership, and land access mitigate vulnerability. These findings highlight the need for integrated and sustainability-oriented policy responses combining climate-smart agriculture, adaptive social protection, early warning systems, and conflict-sensitive programming. Overall, this research advances existing knowledge by delivering rigorous causal insights based on multiple food security indicators and advanced econometric techniques in a highly fragile setting.