A two-season field experiment (2021/2022 and 2022/2023) was conducted on a private farm in the Al-Tour region, South Sinai, Egypt, to evaluate the effects of different irrigation periods and foliar application of magnesium chlorophyllin (Mg-Chl) as well as their interaction treatments on the productivity, water consumption, and water use efficiency of Mentha longifolia grown under a drip irrigation system. The experimental design included three irrigation periods (2, 4, and 6 days) and three concentrations of Mg-Chl foliar spray (0, 0.5, and 1 g/L). The results demonstrated that the treatment combining a 4-day irrigation period with 1 g/L Mg-Chl foliar application significantly improved herb fresh yield, herb dry yield, and oil yield per feddan, as well as water use efficiency. This treatment reduced water consumption by 41.42% and increased productivity by 70.7%, indicating a substantial enhancement in water use efficiency. The average crop coefficient (Kc) for Mentha longifolia under the conditions of the Al-Tour region were 0.95, 0.92, and 0.96 during the initial, development, and maturity growth stages, respectively. Also, the findings demonstrated that the primary chemical constituents of the extracted essential oils were pulegone, 1,8-cineole, menthone, endo-borneol, à-terpineol, and α-pinene.