OBJECTIVES: To assess the impact of multicomponent intervention on knowledge and practice of health behaviors among school children. The secondary objective was to assess mean change in cardiometabolic risk factors such as anthropometric measurements and biochemical profile. METHODS: A cluster-randomized, controlled trial was conducted among adolescents aged 13-18 y from government and private senior secondary schools in Shimla city. Multicomponent health behavioral intervention was delivered through teachers. Subjective and objective measures of knowledge and health behaviors were the primary outcomes. RESULTS: There was no significant effect of intervention on nutrition knowledge adjusted mean difference (aMD) 2.4 (95% CI: -3.7 to 8.7; p = 0.43), and the dietary habits adjusted mean difference 2.9 (95% CI: -0.3 to 6.2; p = 0.08) between the intervention and control group. However, significant improvement in odds of dietary practices 2.4 (95% CI: 1.1 to 5.0; p = 0.03) and decreased odds of consumption of junk food 3.8 (95% CI: 1.6 to 9.3; p = 0.003) was observed. There was no effect on physical activity odds 2.9 (95% CI: 0.8 to 11.6; p = 0.12) or screen time with aMD 0.9 (95% CI: 0.7 to 1.2; p = 0.52). Anthropometric measurements and biochemical profile also did not differ except low-density lipoprotein cholesterol which had significantly lower aMD: -7.2 (95% CI: -13.6 to -1.0; p = 0.02). There was no change in alcohol and tobacco consumption with odds 0.8 (95% CI: 0.6 to 1.2; p = 0.33) and 1.0 (95% CI: 0.7 to 1.5; p = 0.87), respectively after intervention. CONCLUSIONS: Multipronged interventions targeting lifestyle behaviors of adolescents at multilevels are vital to curb rising trends of noncommunicable diseases. This quintessentially calls for wider support across multiple sectors and creation of sustained enabling macro- and micro-environment. The trial is registered in the Clinical Trial Registry of India under the registration number CTRI/2018/01/011312 dated 12/01/2018 Registered, retrospectively.