Water scarcity in arid and semi-arid regions necessitates the adoption of innovative management strategies such as deficit irrigation and the application of organic soil amendments in agriculture. This study aimed to evaluate the main and interactive effects of deficit irrigation and biochar application on growth traits, yield components, and water use efficiency of peppermint. A pot experiment was conducted using a factorial arrangement based on a randomized complete block design with three replications under greenhouse conditions. The first factor was deficit irrigation at three levels (supplying 100%, 75%, and 50% of the plant's water requirement), and the second factor was biochar at three levels (0, 5, and 10% by soil volume). Analysis of variance revealed that the main effect of deficit irrigation on fresh and dry weights of leaves, stems, and roots, as well as water use efficiency based on fresh weight, was significant at the one percent probability level. A significant reduction in the biomass of aerial organs and roots was observed as the irrigation water decreased from 100% to 50% of the water requirement. The main effect of biochar was also significant on all traits, with the highest values of organ fresh and dry weights and WUE obtained with 10% biochar application. The interaction effect of the two factors on root fresh and dry weights was significant, such that under mild stress and in the presence of biochar, the roots exhibited a compensatory response exceeding that observed under non-stress conditions. However, this compensatory mechanism collapsed under severe stress. treatments under severe stress but amended with biochar showed no significant difference in water use efficiency based on dry weight compared to the fully irrigated treatment without biochar. The integration of deficit irrigation with biochar application is an effective strategy for reducing water consumption while maintaining WUE in peppermint cultivation.