Organophosphorus nerve agents pose severe threats to human health and ecosystems due to their extreme toxicity, environmental persistence, and ability to contaminate natural water bodies and their surrounding environments through historical dumping, leakage, and secondary volatilization. Such contaminants can enter aquatic systems, accumulate in sediments, and subsequently volatilize from water surfaces, posing long-term risks to water security and ecosystem stability. However, existing detection techniques are often limited by bulky instrumentation, complex operation, and the inability to provide continuous, on-site monitoring in natural environments. Herein, we report a nanobionic plant–based sensing strategy designed for environmental and water-security–oriented monitoring of nerve agent vapors. Terbium-based metal–organic frameworks (Tb-BDC MOFs) were integrated in situ into living plant leaves, enabling sensitive fluorescence quenching in response to diethyl chlorophosphate (DCP), a representative sarin simulant. A node-metal substitution strategy using Zr doping optimized the sensing performance, with density functional theory calculations revealing symmetry breaking, orbital reorganization, and reduced adsorption energy toward DCP. Leveraging plant transpiration, the nanobionic leaves actively collect and enrich volatilized contaminants originating from water bodies and surrounding environments, achieving ultrasensitive detection superior to conventional powder-based test strips. Furthermore, a remotely deployable monitoring system combining pre-deployed nanobionic plants, a UV-enabled drone, and a mobile application enables real-time, unmanned assessment of chemical threats. This work highlights a sustainable, scalable approach for safeguarding water resources and adjacent ecosystems through long-term environmental surveillance.