This study investigates the effects of chitosan (Cs) and chitosan nanoparticles (CsNPs) on mitigating salinity stress in Phaseolus vulgaris L. plants. Salinity stress negatively impacts plant growth, yield, and physiological and biochemical traits. The study found that both Cs and CsNPs significantly improved plant growth, yield, and various physiological and biochemical parameters under salt stress conditions. Specifically, CsNPs showed more beneficial effects than Cs in enhancing plant height, shoot length, seed yield, and total soluble sugars (TSS). Additionally, CsNPs reduced hydrogen peroxide, lipid peroxidation, and electrolyte leakage, while increasing proline content. The study concludes that CsNPs are more effective in mitigating salt stress in P. vulgaris L. plants compared to Cs, suggesting their potential use in improving crop tolerance to saline soils. However, further research is needed to determine the long-term impact of CsNPs on crop productivity.This study investigates the effects of chitosan (Cs) and chitosan nanoparticles (CsNPs) on mitigating salinity stress in Phaseolus vulgaris L. plants. Salinity stress negatively impacts plant growth, yield, and physiological and biochemical traits. The study found that both Cs and CsNPs significantly improved plant growth, yield, and various physiological and biochemical parameters under salt stress conditions. Specifically, CsNPs showed more beneficial effects than Cs in enhancing plant height, shoot length, seed yield, and total soluble sugars (TSS). Additionally, CsNPs reduced hydrogen peroxide, lipid peroxidation, and electrolyte leakage, while increasing proline content. The study concludes that CsNPs are more effective in mitigating salt stress in P. vulgaris L. plants compared to Cs, suggesting their potential use in improving crop tolerance to saline soils. However, further research is needed to determine the long-term impact of CsNPs on crop productivity.