<p>This research aimed to improve the physiological response of <i>Nigella sativa</i> to drought stress using arbuscular mycorrhizal fungi, phosphate-solubilizing bacteria, and zinc foliar application. The results demonstrated that the reduction in irrigation water significantly affected photosynthetic pigments, relative water content, electrolyte leakage, proline content, leaf-soluble sugars, soluble proteins, biological yield, and grain yield. In addition, in 2018 and 2019 years elevated drought stress decreased total chlorophyll (63 and 70%), carotenoids (59 and 59%), relative water content (37 and 32%), soluble proteins content (36 and 37%), biological performance (48 and 45%), and grain yield (64 and 48%). Furthermore, it increased electrolyte leakage (37 and 35%), proline (132 and 138%), and soluble sugars content (65 and 56%). The combined use of arbuscular mycorrhizal fungus (AMF) and Phosphate barvar-2 bio-fertilizer (PB2) (containing two types of phosphate-solubilizing bacteria: <i>Pseudomonas putida</i> P13 and <i>Pantoea agglomerans</i> P5) alleviated for the decrease in the measured traits. Consequently, applying bio-fertilizer increased biological performance (24 and 26%) and grain yield (30 and 27%) and decreased electrolyte leakage (18 and 20%) compared to no bio-fertilizer application. Moreover, the combination of AMF and PB2 increased the grain nitrogen (66 and 40%) and grain phosphorus (18 and 20%). Zinc foliar application increased grain elements content, photosynthesis pigment, proline, soluble sugars content, soluble protein content, relative water content and biological performance. Furthermore, it decreased electrolyte leakage. Bio-fertilizers and zinc foliar application mitigated the detrimental effects of drought stress on the quality, grain yield, and biological performance of black cumin by improving the physiological mechanisms.</p>