<p>Food insecurity and malnutrition, including hidden hunger and child stunting, remain critical challenges in Rwanda’s semi-arid regions. While traditional metrics prioritize yield, this study evaluates Nutritional Water Productivity (NWP) as a holistic approach that integrates nutritional value with water-use efficiency. This study provides the first multi-nutrient NWP assessment integrating C3 and C4 crops under drip irrigation within Rwanda’s semi-arid regions, thereby addressing a major research gap in nutrition-sensitive water productivity assessment. The experiment, conducted in Huye District using a Randomized Completely Block Design (RCBD), compared Maize and Brachiaria (C4 plants) with Beans, Soybeans, and Irish Potato (C3 plants) under both drip irrigation and rainfed conditions. The study uniquely contrasts C3 and C4 crop pathways under precision irrigation and rainfed water stress, enabling clearer understanding of their differential physiological responses. Seven nutritional parameters, including crude protein, energy, starch, carbohydrates, crude fiber, crude fat, and ash, were analyzed based on actual evapotranspiration. Findings revealed that rainfed treatments outperformed irrigated treatments across all nutritional values, indicating a concentration effect where nutrients densify under moderate water stress. This explanation is supported by physiological evidence of nutrient densification under mild water deficit, particularly in C3 legumes and C4 grasses. Soybeans proved most efficient for protein delivery (2.18&#xa0;g/kg/mm), while Maize excelled in energy and carbohydrate productivity (3.05&#xa0;g/kg/mm). Integrating NWP into agricultural practices is vital for modernizing farming in water-scarce areas. By prioritizing crops that maximize nutrition per drop specifically C4 plants for energy and C3 legumes for protein, Rwanda can align its agricultural output with national strategies such as NST2, PSTA5, and Vision 2050 to enhance long-term food resilience and combat malnutrition.</p>