Nanotechnology is emerging as a transformative tool in modern agriculture, offering novel strategies to enhance crop protection, growth, and sustainability. This chapter provides a comprehensive overview of the applications, mechanisms, and future potential of nanomaterials in plant systems. Nanomaterials, classified into organic, inorganic, and hybrid types, exhibit unique physicochemical properties such as high surface-area-to-volume ratios, mobility, and surface functionalization that make them highly effective for agrochemical delivery, pathogen control, and stress mitigation. Their multifunctionality enables improved targeting, controlled release, and reduced environmental impact compared to conventional agrochemicals. The chapter details the mechanisms through which nanomaterials influence plant health, including enhanced photosynthesis, hormonal regulation, root development, and activation of antioxidant defences. In crop protection, nanopesticides and antimicrobial nanoparticles like Ag, ZnO, and CuO disrupt pathogen physiology via membrane damage, ROS generation, and biofilm inhibition. Furthermore, nanosensors offer real-time disease detection and environmental monitoring, enabling data-driven crop management. Nanofertilizers contribute to nutrient use efficiency through slow-release and foliar-penetrating formulations, while nanopriming and foliar or root uptake pathways enhance plant resilience to abiotic stresses such as drought, salinity, and heavy metals. Despite these advantages, challenges remain regarding the long-term ecological impacts, translocation behaviours, and regulatory oversight of nanomaterials. Public concerns about biosafety and the lack of harmonized regulatory frameworks also hinder widespread adoption. The chapter concludes by highlighting future directions, including the development of smart, responsive, and biodegradable nanomaterials integrated with digital agriculture platforms such as IoT and AI. Collectively, these advances position nanotechnology as a promising solution for developing sustainable, climate-resilient, and precision-based agricultural systems.