Background: Over recent decades, with the increase in the prevalence of childhood overweight/obesity, the prevalence of pediatric non-alcoholic fatty liver disease (NAFLD) has increased. Objectives: The aim of this study was to investigate the prevalence of NAFLD and its predisposing factors in overweight and obese children of Urmia, Northwest of Iran. Methods: In this cross-sectional study, a total of 843 children aged 2 to 19 years were recruited out of 10800 children referred to the Digestive Disease Clinic of Shahid Motahari Hospital during 2016-2017. Anthropometric and laboratory measurements and abdominal ultrasound were performed for the children. Demographic data and their medical history were collected by a questionnaire. Unconditional logistic regression was used to predict the predisposing factors of NAFLD. Results: Fatty liver was diagnosed by ultrasound in 9.5% of overweight and 21.4% of obese children. The prevalence of NAFLD in obese children was 9.26% for the 2-5.9-year age group, 22.3% for the 6-11.9-year age group and 35.5% for the 12-19-year age group. Compared to the normal liver group, the adjusted odds ratios (ORs) [95% confidence interval (CI)] for predictive factors of NAFLD were as follows: ALT