The convergence of nanotechnology and precision agriculture is redefining the future of sustainable food systems. As global agricultural systems face mounting pressures from climate volatility, resource depletion, and population growth, nanosensors engineered at the molecular scale offer a revolutionary toolkit for real-time, high-resolution monitoring of soil nutrients, crop physiological status, and water dynamics. Despite burgeoning research, a critical synthesis of how these nanoscale devices functionally integrate across the agro-ecosystem from rhizosphere to canopy, from lab to field remains absent. This review fills that void by providing a transdisciplinary analysis of nanosensor platforms, deployment architectures, and data ecosystems tailored for precision agriculture. We evaluate cutting-edge materials including plasmonic nanostructures, electrochemical nanowires, enzyme-functionalized quantum dots, and molecularly imprinted polymers for their sensitivity, environmental stability, and field-deployable form factors. Novel insights are presented on overlooked challenges: nanomaterial aging under UV/soil pH, biofouling interference, energy autonomy for remote sensing, and regulatory fragmentation across jurisdictions. Beyond technology, we examine socio-technical adoption barriers and propose scalable manufacturing and farmer-engagement models. This review does not merely catalog innovations it constructs a unified framework for evaluating “agricultural nanosensor readiness,” identifying critical gaps and accelerators for real-world impact. By bridging materials science, agronomy, data engineering, and policy, we chart a course toward intelligent, self-regulating farms where nanosensors serve as the nervous system of sustainable agriculture transforming data into decisions, and innovation into resilience.