Purpose: The present study is focused on understanding weight perception related with individual- and school-level multifactorial origins, underestimated and overestimated respectively, in normal body weight adolescents. Methods: Using the 2017 Korea Youth Risk Behavior Web-based Survey data of 45,902 students from 799 secondary schools, a multilevel multinomial logistic regression analysis was performed where adolescents (level1) were nested within schools (level 2). Results: At the school level, the average school body mass index (BMI, kg/m²) and physical education were associated with weight perception among both boys and girls. In boys, geographic areas were associated with weight underestimation. At the individual level, perceived economic status, weekly allowance, BMI (kg/m²), smartphone usage time (hrs/day) and perceived stress were associated with weight perception among both boys and girls. Age, paternal education, academic achievement and alcohol use were associated with weight perception among girls, while part-time job and physical activity were associated with weight perception among boys. Conclusion: Our findings underscore the importance of individual- and school-level environments in developing correct weight perception and have implications for school health education to establish healthy lifestyle behaviors for all adolescents.