Zinc oxide nanoparticles (ZnO-NPs) has been demonstrated to positively regulate plant tolerance to multiple environmental stresses. However, till date little information has been gained regarding the role of ZnO-NPs in the salt stress regulation in plants. Hence, the objective of our study was to investigate the role of ZnO-NPs in the regulation of salt tolerance in tomato (Lycopersicon esculentum Mill.). In this regard, the tomato plants were subjected to salt stress by using NaCl (150 mM) at the time of transplantation [15 days after sowing (DAS)]. Foliar application of ZnO-NPs at different levels viz., 10, 50 and 100 mg/L in the presence/absence of NaCl (150 mM) was carried out at 25 DAS and sampling was done at 35 DAS. Results of our study revealed that foliar spray of ZnO-NPs significantly increased shoot length (SL) and root length (RL), biomass, leaf area, chlorophyll content and photosynthetic attributes of tomato plants in the presence/absence of salt stress. Besides, the application of ZnO-NPs mitigates the negative impacts of salt stress on tomato growth, and enhanced protein content and antioxidative enzyme activity such as peroxidase (POX), superoxide dismutase (SOD) and catalase (CAT) under salt stress. In conclusion, the ZnO-NPs plays an important role in the alleviation of NaCl toxicity in tomato plants. Hence, the ZnO-NPs can be used to boost the growth performance and mitigate the adverse effects caused by NaCl in tomato.