International food security is severely threatened by viral diseases in plants, as they decrease crop productivity and quality. Traditional chemical control methods often fall short because they can harm the environment, are somewhat ineffective, and do not fully eliminate viral pathogens. In this context, chitosan nanoparticles (CNPs) have recently been proposed as a new, practical, and eco-friendly approach to managing plant diseases. Chitosan, derived from chitin, is an antimicrobial, biodegradable, and biocompatible polymer. When engineered at the nano-level, chitosan becomes more soluble, bioavailable, and capable of delivering bioactive agents more effectively. CNPs exhibit a broad spectrum of antiviral actions, both directly by suppressing viral replication or disrupting virion structure, and indirectly by activating the plant's defense system, such as systemic acquired resistance (SAR). They may also serve as carriers to deliver new molecules, like RNA interference (RNAi)-based agents, to specifically silence plant virus genes. Beyond their pathogen control capabilities, CNPs have been found to promote plant growth by enhancing nutrient uptake and stimulating development. Despite these promising features, challenges persist in standardizing nanoparticle production, scaling up manufacturing, ensuring affordability, and obtaining regulatory approval. Their impact on plant tissues, soil ecosystems, and non-target organisms is still not fully understood. Nonetheless, ongoing efforts in designing intelligent nano-formulations, integrating precision agriculture systems, and applying combination therapies suggest that future CNPs could play an even greater role in sustainable crop protection. Overall, chitosan nanoparticles provide a highly versatile, environmentally friendly, and scientifically validated platform for managing viral diseases in plants. Their ability to boost plant immunity and deliver antiviral compounds underscores their potential as a cornerstone of environmentally sustainable farming practices in the future.