Soils have been getting worse over time, which has led to lower crop yields and nutritional value. This is because of too many conventional fertilizers, anthropogenic activities, and climate change. Soil salinity is also a big problem and challenge for agricultural scientists. To address this issue, nanoparticles are gaining a reputation in agriculture that can enhance salinity tolerance in crops, especially at early growth stages. A pot experiment was conducted at Post Agricultural Research Station (PARS), Faisalabad to assess the impact of iron oxide nanoparticles (0, 15, and 30 ppm) and four levels of salinity (0, 50, 100 and 150 mM) on morphological, physiological and yield traits of maize (Zea mays L.) in salinity stress. Salinity stress significantly negatively affected the growth attributes, photosynthetic pigments, ion content (Na⁺, K⁺, and Ca²⁺) of maize plants. Salinity has also increased the levels of MDA, H₂O₂, and Na⁺ ions. The application of iron oxide nanoparticles through foliar spray had a notable impact in enhancing the growth and yield of the tested maize variety. It was achieved by promoting the activities of antioxidant enzymes, increasing photosynthetic pigments, and elevating K⁺ and Ca²⁺ ion levels under both normal and salinity-stressed conditions. Additionally, iron oxide nanoparticles mitigated the adverse effects of salinity stress by effectively reducing Na⁺ ion concentration, MDA levels, and H₂O₂ concentration. Among the different concentrations tested, 30 ppm of iron oxide nanoparticles proved best in alleviating the negative impacts of salinity stress in maize. Thus, field use of 30 ppm iron oxide nanoparticles as foliar spray could effectively mitigate salinity stress in maize.