Light intensity significantly influences plant growth in hydroponic green fodder systems, yet research exploring the growth dynamics and nutrient accumulation in hydroponically grown barley under various light conditions has been limited. This study investigated the impact of different light intensities—0, 100, 200, and 300 μmol/m2/s—on the nutritional composition and quality of hydroponic barley fodder. Assessments were made on biomass production, physiological responses including photosynthetic parameters, and nutritional components such as essential amino acids five days post-treatment. The findings indicated that increasing light intensity boosted photosynthetic activity, expanded leaf area, enhanced root length, and promoted biomass accumulation. However, the highest intensity tested, 300 μmol/m2/s, led to significant chlorophyll degradation, increased water loss, and induced oxidative stress, adversely affecting fodder quality and reducing essential amino acids. In contrast, an intensity of 200 μmol/m2/s was identified as optimal for promoting robust barley growth through principal component analysis. This optimal setting supported vigorous growth and ensured the production of nutrient-rich, high-quality fodder, providing a basis for scaling up production efficiently. This research offers crucial insights into optimizing light conditions to maximize both the yield and nutritional quality of hydroponically grown barley fodder, presenting a significant step forward in enhancing hydroponic farming practices.