Childhood undernutrition remains a major public health challenge in India, contributing significantly to morbidity, mortality, impaired physical growth, and long-term cognitive and socioeconomic consequences. Ayurveda describes a comparable clinical condition termed Karshya, characterized by emaciation, tissue depletion, weakness, poor appetite, and delayed growth. Traditional Ayurvedic nutritional formulations emphasizing Brimhana, Balya, and Rasayana principles offer sustainable, culturally acceptable strategies for addressing undernutrition. Vajranna Modak, a nutrient-dense preparation composed of Bajara (Pennisetum glaucum), Amalaki (Emblica officinalis), Groundnut (Arachis hypogaea), Guda, and Ghrita, represents a food-based therapeutic intervention integrating nutritional adequacy with Ayurvedic principles. This review critically examines the epidemiology of childhood undernutrition, the Ayurvedic conceptual framework of Karshya, the nutritional and pharmacological rationale of Vajranna Modak, and its potential role as a community-based public health initiative for children aged 2–12 years.