<p>Myo-inositol is a ubiquitous constituent with an imperative function in regulating plant acclimatization to stress conditions. However, myo-inositol’s role in resistance against drought stress in mungbean has not yet been reported. This study aims to examine the effects of the exogenous application of myo-inositol on growth, photosynthetic efficiency, and antioxidant machinery in mungbean (<i>Vigna radiata</i> L.) under drought stress. The results highlighted that drought stress, induced by polyethylene glycol (PEG), significantly reduced shoot and root length, chlorophyll and carotenoid contents, as well as relative water content (RWC), with more pronounced effects observed at 5% and 10% PEG concentrations compared to the control plants. It also led to a considerable increase in the formation of reactive oxygen species (ROS) along with elevated production of malondialdehyde (MDA) compared to control plants. However, exogenous myo-inositol not only significantly ameliorated plant growth, photosynthetic pigment levels, and RWC in drought-stressed plants but also significantly reduced MDA content and H₂O₂ levels, thereby enhancing membrane stability under drought stress. Myo-inositol supplementation upregulated the activity of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX), which protected the cellular membranes from oxidative damage under drought conditions. The current study's findings point towards the positive behavior of exogenous myo-inositol in maintaining osmotic balance, antioxidant, and photosynthetic machinery against PEG-induced drought stress in mungbean. </p>