Salinity stress is a major abiotic factor that significantly reduces crop yields by affecting plant growth and physiological processes. Current common approaches to manage salinity stress are inadequate and largely ineffective for ecological reasons. In this context, chitosan nanoparticles (CNPs) have gained popularity as an environmentally friendly and effective means of combating salt-related disorders. Chitosan, a naturally occurring chitin- derived biopolymer, is biocompatible, biodegradable, and inherently bioactive, and exists in an optimized nanoparticulate form that offers greater surface area and targeting capabilities. This chapter explores the potential of CNPs in combating salinity stress by modulating physiological, biochemical, and molecular processes in plants. The application of CNPs can enhance seed germination, nutrient uptake, ion homeostasis, and antioxidant defense system under salinity conditions. They also promote osmolyte accumulation and regulate the expression of stress-responsive genes, thereby boosting plant tolerance. CNPs have been shown to improve the growth and yield of crops such as rice, wheat, tomatoes, and maize when applied as a foliar spray or soil additive in response to salt stress. In addition, CNPs can serve as carriers for growth regulators, nutrients, and other bioactive compounds, offering further avenues for tailored stress regulation. Although promising, issues such as dosage optimization, plant-nanoparticle interactions, and long-term ecological effects need to be further investigated. Overall, CNPs have the potential to be a sustainable and innovative approach to alleviating salinity stress, helping to secure global food supplies and promote sustainable agriculture.