Plants are highly sensitive to environmental stresses, including salinity, drought, extreme temperatures, heavy metals, flooding, fluctuating light, and ultraviolet radiation. These stresses significantly influence plant growth and productivity, posing challenges to global agriculture. Nanomaterials, due to their unique physicochemical and biological properties, offer promising solutions for enhancing plant stress tolerance and enabling real-time stress monitoring. Here, we provide an integrative review of the direct and indirect roles of nanomaterials in plant stress responses, highlighting their molecular mechanisms, such as ROS modulation, hormonal signaling, and ion homeostasis regulation. We further discuss the emerging applications of nanosensors for intracellular and environmental monitoring, emphasizing multifunctional, real-time detection strategies. Finally, we propose a conceptual framework integrating nanomaterials and nanosensors, aiming to bridge laboratory research with field applications, and outline key challenges and opportunities for sustainable and precise agriculture. © 2026 Elsevier B.V.