Adolescent obesity is becoming more prevalent due to changing lifestyles, and it has negative effects like a higher incidence of non-communicable diseases. Identification of risk factors leading to the rapid rise in adolescent obesity is a crucial first step in preventing and controlling it. Therefore, this study was carried out in Rajkot. The primary objective was to find the prevalence of obesity among the school going adolescents aged 14-19 years and to identify the determinants associated with obesity. A cross-sectional study among the adolescents studying in school was carried out by using multistage sampling method. A predesigned questionnaire with personal and family history and details of dietary habits and physical activity was filled by the participants. Anthropometric measurements of the participants including height, weight, waist and hip circumference were taken. Out of total 1120 participants, 25.8% were underweight, 11.1% were overweight and 6.9% were obese. Overweight and obesity was significantly associated with the occupation of participant’s father and mother, lack of physical activity, more screen time, non-vegetarian diet and daily consumption of carbonated drinks and chocolates. (p<0.001). The determinants like physical activity and dietary habits were found to be associated with overweight and obesity. Modifying one's lifestyle can be very helpful in preventing adolescent obesity as well as developing healthy routines for later life.