Salinity is one of several climate change impacts. Salinity in the water and soil has a negative effect on the growth and productivity of horticultural crops. Arginine has surfaced as a non-toxic plant growth governor that augments the resistance of plants to salt stress. Our objective was to assess the effects of exogenous foliar application of arginine on growth, yield, osmoprotectants and biochemical traits, as well as an antioxidant system of NaCl salt-stressed pot marigold plants. Two successive (2020/2021-2021/2022) pot trials were conducted using four NaCl salt concentrations (50, 100, 150 mM, plus control; non-NaCl salt) combined with three arginine levels (3, 6 mM, plus control; non-arginine sprayed plants). Higher NaCl salinity concentration showed a significant decrease in plant growth, yield, leaf total chlorophylls, and nutritional status, while exhibiting a substantial increase in Na⁺, Cl^-, osmoprotectants and biochemical constituents, in addition to antioxidant activity. Exposing plants to 150 mM of NaCl salt decreased herb dry weight by 34.7%, No. of inflorescences by 30.4%, but increased Na content by 200.7%, Cl by 36.7%, and proline by 216.3% compared to control. Nevertheless, the foliar arginine application enhanced growth, yield, and antioxidant activity. Higher arginine treatment (6 mM) increased flower contents of total carotenoids by 3.67%, phenolics by 8.77%, flavonoids by 11.8%, DPPH by 5.25%, and 13.6% accumulation of free amino acids in leaves compared to untreated plants. Finally, exogenous arginine treatment had a mighty potential to encounter the effects of NaCl salt stress on pot marigold plants.