The aim of the present study was to analyze the relationship between time spent engaged in sedentary behaviors, type of diet, and overweight in adolescents. A cross-sectional study using data from the Longitudinal Study on Sedentary Behavior, Physical Activity, Eating Habits, and Health of Adolescents - LONCAAFS Study. A total of 1,438 adolescents (10 to 14 years old) from public schools in the city of João Pessoa, Brazil, participated in the study. To evaluate the combined effects of excessive time in sedentary behavior and consumption from two food groups: Convenience and Prudent on overweight, we performed multiple logistic regression analyses, adjusted for energy, level of physical activity, sex, and age. Excessive time in sedentary behavior increased the chance of adolescents being overweight by 37% (OR = 1.37; 95%CI: 1.04-1.80). This chance increased to 43% when the adolescents were simultaneously engaged in excessive sedentary behavior and had high consumption of the Convenience food group (OR = 1.43; 95%CI: 1.05-1.94) and increased to 39% on those who engaged in excessive sedentary behavior and had low consumption of foods from the Prudent (OR = 1.39; 95%CI: 1.04-1.84). Excessive sedentary behavior is associated with being overweight and the chance increases with the consumption of convenient foods.