Purple basil (Ocimum basilicum L.) is a medicinal plant widely recognized for its richness in bioactive compounds; however, its production in semi-arid regions is often constrained by soil and/or irrigation water salinity. Micronutrient fertilization may contribute to plant stress alleviation under salinity, since elements such as Mn, Mo, and Zn are involved in essential processes related to photosynthetic metabolism and physiological adjustment. This study aimed to evaluate the short-term effects of Mn, Mo, Zn, and their combinations on growth, gas exchange, and relative chlorophyll indices of purple basil plants subjected to severe NaCl stress under greenhouse conditions. The experiment was conducted under greenhouse conditions for 30 days in a randomized block design with nine treatments and four replicates: a non-saline control without micronutrients, a saline control without micronutrients, and plants exposed to 100 mM NaCl with substrate application of Mn, Mo, Zn, MoMn, ZnMo, ZnMn, or ZnMoMn. Micronutrient sources were applied to the substrate at 3.5 g kg⁻¹ according to each treatment. Fertilization with Mn, Mo, Zn, and their combinations enhanced plant stress alleviation under salinity compared with the saline control without micronutrients, with positive responses in growth and physiological performance, including increases in chlorophyll indices. The double combinations MoMn, ZnMo, and ZnMn attenuated the effects of NaCl, especially by increasing leaf area. Mn stood out for increasing net photosynthesis and water-use efficiency, whereas Mo and ZnMo were associated with higher relative chlorophyll indices. Although the triple combination ZnMoMn improved some traits compared with the saline control, its lower efficacy relative to selected single or double applications may indicate that the simultaneous supply of the three elements reduced specific synergistic effects, possibly due to nutritional imbalance or antagonistic interactions among micronutrients under severe salinity. Overall, micronutrient fertilization, particularly through specific double combinations, may contribute to short-term mitigation of NaCl-induced stress responses under controlled greenhouse conditions.