Due to the limited availability of fresh water, it is imperative to find methods for balancing the population's resource management and utilise salt water instead of fresh water while irrigating plants. Sage plant is one of the most important medicinal plants suitable for expanding their cultivation in Salt-affected new reclaimed lands. Consequently, a field trial during two consecutive seasons of 2019 and 2020 was implemented under a split-plot design, aiming to assess the role of biochar addition (0, 2, 4 ton fed^-1) in mitigating the drastic effect of saline water [450 (as control), 1000, 2000, 3000, and 4000 mgL^-1]. Various parameters, including plant height, number of branches, dry weight, essential oil percentage and yield as well as chlorophyll a and b, carotenoids, N, P, K, and carbohydrates were determined.  Additionally, indicators of plant tolerance to salinity, such as proline and MDA (malondialdehyde) were also determined. The results indicate a decline in growth traits, photosynthetic pigments, and chemical constituents with an increase in the salinity level of irrigation water. Conversely, the values of proline and MDA exhibited an upward trend as the salinity of irrigation water increased. On the other hand, the addition of biochar enhancing the performance of sage under salinity conditions. The highest values for the studied traits (except for proline and MDA which exhibited the opposite trend) were observed with the highest biochar rate (4 ton fed^-1), followed by plants treated with 2 ton fed^-1, and finally, the control treatment. These findings not only contribute to our understanding of sage plant adaptation to saline conditions but also highlight the potential of biochar as a beneficial amendment in enhancing plant performance under salinity stress.