Climate change-driven water scarcity poses a major threat to horticultural productivity. This study explores rootstock grafting as a drought mitigation strategy in two major vegetable crops—tomato (Solanum lycopersicum) and okra (Abelmoschus esculentus). Drought-tolerant rootstocks were grafted with commercial scions and subjected to controlled drought stress. Grafted plants exhibited improved physiological performance, including higher relative water content, chlorophyll fluorescence (Fv/Fm), and stomatal regulation, compared to non-grafted controls. Gene expression analysis revealed significant upregulation of stress-responsive genes (e.g., DREB1, MAPK, PIP2;1) in the scion, indicating effective long-distance signaling and rootstock-induced stress priming. Proximate analysis of fruit revealed enhanced protein, fiber, and micronutrient content under stress. Yield assessments further confirmed superior fruit set and biomass in grafted plants under drought conditions. These findings underscore the role of rootstock–scion communication in stress adaptation and nutritional resilience, offering a viable approach to climate-smart vegetable production.