Junk food is high in calories but low in essential nutrients, posing a health risk particularly during adolescence. Many low and middle income countries, like Nepal, are experiencing a nutritional shift along with a rising consumption of junk food among school-aged adolescents. Despite its known health risks, junk food remains popular among adolescent school students. This study aims to determine the prevalence of junk food, its consumption patterns and associated factors, among secondary school students of Banganga, Nepal. Methods: A school-based descriptive cross-sectional study was conducted among 270 secondary school students in Banganga municipality ward number 2, selected using stratified random sampling. Data were collected via a self-administrated structured questionnaire. Bivariate and multivariate logistic regression analyses were done using IBM-SPSS version 20. Results: The prevalence of junk food consumption among secondary school students was 74.4%. Fast food was the most consumed category (74.13%) and the most frequently consumed items were biscuit, chocolate, coke and chowmein. Sex, grade, father’s occupation, living status and parent’s habit of junk food consumption were significantly associated with junk food consumption at 95% of confidence interval. Conclusion: The high prevalence of junk food consumption among adolescents highlights an urgent need for collaborative efforts between parents, school administrations and other relevant stakeholders to promote healthier food options in school cafeterias and encourage homemade, nutritious foods.