BACKGROUND Childhood obesity, caused due to excessive fat accumulation, is one of the leading causes of preventable deaths associated with several non-communicable diseases. In Nepal, there is limited data available on the status of overweight and obesity among school children. The objective of this study was to find out the prevalence of childhood overnutrition among school going children in a municipality. METHODS A descriptive cross-sectional study was conducted from June 2019 to July 2019, in four schools of a municipality selected by simple random sampling. Ethical approval was obtained from Nepal Health Research Council (Registration number 380/2019). Data was collected using census sampling from children aged 5-18 years through self-administered questionnaires to the children's parents. The data was entered into the Statistical Package for Social Sciences for analysis. Point estimate at 95% confidence interval was calculated along with frequency and proportion for binary data. RESULTS Out of 379 school children, the prevalence of overnutrition was found to be 38 (10.03%) (95% Confidence Interval= 7.01-13.05). Prevalence of overnutrition was highest in children of age group 10-13 years 23 (60.5%), in females 27 (71.1%), those consuming junk food 4-6 times weekly 14 (36.8%) and those performing daily physical activity less than 60 minutes 24 (63.2%). CONCLUSIONS The prevalence of childhood overnutrition is similar in comparison to other studies done in similar settings.