Many parts of the world are experiencing water shortages for agriculture. Since spearmint is a significant plant that uses much water, an enhanced irrigation management strategy is required. Soil additives with organic matter could potentially boost spearmint (Mentha spicate L.) water productivity. A field experiment was established under newly reclaimed soil throughout two growing seasons. This is to elucidate the influence of biochar, compost, and their combination under different irrigation water levels (120, 100, and 80% of crop evapotranspiration “ETo") on spearmint yield, quality, and irrigation water productivity. The results of a split-plot design experiment indicated that the combination outperformed the individual application of compost or biochar under different irrigation levels regarding the studied variables. However, higher fresh herb yield (6.4 and 7.79 ton/ha) was recorded in the treatment receiving biochar mixed with the compost under 120% ETo in both seasons. Also, biochar mixed with compost offered the highest values of the essential oil component; carbon, under 80% ETo. Moreover, results showed that biochar and compost positively affected spearmint production by boosting leaf chlorophyll content and increasing nutrient absorption. In both seasons, data revealed that spearmint water productivity under 80% ETo was reduced by 18.28% and 7.92% relative to 100% ETo as well as 23.17% and 24.75% compared to 120% ETo using biochar combined with compost. Using a combination of compost and biochar is suggested as an extremely efficient way to boost spearmint yield and water productivity.