India's indigenous groups remain vulnerable to malnutrition, despite economic progress, reflecting the reliance on traditional agriculture and the problems of poverty and inadequate education and sanitation. This mixed-methods study analyzed the incidence, causes and determinants of chronic malnutrition, measured through stunting, thinness and underweight among adolescent indigenous girls in Telangana. Using 2017 data on 695 girls aged 11-18 years from 2542 households, the analysis showed that 13% had normal nutritional status, while 87% were stunted, underweight or thin. Early adolescents (11-14 years) had higher underweight prevalence (24.4%), while late adolescents (15-18 years) showed greater stunting (30%). Regressions identified key influencing factors. Higher education levels of heads of households and the girls themselves alongside household toilet access significantly improved nutritional status and reduced stunting and underweight. The sociocultural emphasis on starchy staple-based diets and early marriage also impacted outcomes. Tackling this crisis requires mainstreaming nutrition across development agendas via comprehensive policies, education, communication and community participation. Further research can guide context-specific solutions. But, evidence-based investments in indigenous education, livelihoods, sanitation and women's empowerment are the first steps. Nutrition-sensitive development is indispensable for indigenous groups to fully participate in and benefit from India's progress.