Waist-based indicators of obesity are being used to detect central obesity and are predictive for metabolic syndrome (MS). The aim of the study is to assess the basic anthropometric indices in children, to determine the prevalence of overweight and obesity, and to determine the association between various waist-based measurements and body mass index (BMI). A cross-sectional study was conducted among children aged 10 to 15 years attending government corporation schools in Chennai. Basic anthropometric measurements were taken. BMI, waist circumference/height ratio (WHtR), and waist circumference/hip circumference ratio (WHR) were calculated. The percentiles (Indian reference cutoffs) were determined for waist circumference (WC) and BMI. The prevalence of overweight and obesity was determined and compared to waist-based parameters. Of 820 children, males constituted 47.1%. Stunting was seen in 9.8% and 7.8% were underweight. 8.2% had BMI less than the 3rd percentile. The prevalence of overweight and obese children was 9% and 3.2%, respectively, with female predominance. The majority had WC less than the 5th percentile. The prevalence of children under risk for MS based on WC >70th percentile was 4.5% and based on WHtR >0.5 was 8.2%. A significant association was identified between all waist-based anthropometric measurements to detect children at risk for MS and overweight/obese children as per BMI category. WHtR >0.5 was an indicator of overweight/obese children in logistic regression analysis. Early identification of children at risk of MS would require a combination of BMI to detect general obesity and waist-based anthropometric measurements to identify central obesity.