The uniqueness and novelty of this study lies in the ability of Mentha longifolia leaves extract (MLLE) to synthesize bimetallic NPs (NPs) of zinc oxide and magnesium oxide as nanocomposite (ZnO/MgO NPs) for the first time. Medicinal plants extracts are a more environmentally friendly method of creating NPs than physical or chemical methods. The specific objectives of the research were employed this nanocomposite compared to plant extract as antibacterial, anti-diabetic, antioxidant agents. Also, the possibility of using this nanocomposite as plant stimulator for reducing saline water stress on economic plants to cope with the scarcity of freshwater in the agricultural sector. In comparison to nanocomposite, MLLE exhibited high inhibition zones 28 ± 0.1, 26 ± 0.2, 26 ± 0.1, 25 ± 0.2, 25 ± 0.1 and 24 ± 0.1 mm in medium inoculated by E. faecalis, E. coli, S. typh, M. circinelloid C. albicans, and S. aureus, respectively. It was shown from the DPPH data that ZnO/MgO NPs' IC