Background: Co-morbidities in adulthood is a significant problem and is associated with obesity during adolescent. Methods: This 3-months randomised controlled trial was aimed at determining the effectiveness of having internet-based intervention (obeseGO!) toward obesity among adolescents in Kuala Lumpur. Forty seven students were assigned randomly to the obeseGO! (intervention) group for internet-based intervention i.e., information on healthy lifestyle and diet were provided via the internet. Fifty students were assigned to the control group, where pamphlets containing health education were provided to these students. The measurement of body mass index (BMI), waist circumference, and the body fat percentage was taken at baseline and after 12 weeks of intervention. Results: The multivariate analysis of variance (MANOVA) analysis found that obeseGO! had a small effect in reducing BMI, waist circumference and body fat percentage. Conclusion: The internet-based obesity intervention program may be an effective medium for promoting healthy diet and physical activity among the obese adolescents.