Objective: To verify the effects of physical exercise using a gamified exergame on pulmonary function and cardiorespiratory fitness of adolescents with overweight in their school environment. Methods: This controlled clinical trial was conducted in two schools. Adolescents aged 10-16 years with overweight or obesity were eligible. Control group received physical education classes and orientations provided by school. Intervention group performed physical exercise using the exergame associated with gamification in school, with four adolescents per group, three times per week during eight consecutive weeks. For gamification, the performance was scored every week, generating a weekly classification and a final at the end of the study. Cardiorespiratory fitness was assessed indirectly using the maximal oxygen consumption (VO2max) from the 20-meter shuttle run test. Pulmonary function was assessed using manovacuometry and spirometry. Results: Intervention and control groups were composed of 36 and 27 adolescents, respectively. Adolescents that performed the exergame presented lower forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) and higher FEV1/FVC ratio than the control group. Intervention group increased FEV1 (p = 0.041) and maximal expiratory pressure (PEmax) (p = 0.009), decreased body mass index (BMI) (p < 0.001), and improved VO2max (p = 0.007), compared to baseline. Control group increased FEV1 (p = 0.021), FVC (p = 0.014), and FEV1/FVC ratio (p = 0.033) and decreased BMI (p < 0.001), compared to baseline. Conclusion: Exergame improved pulmonary function, and intragroup analysis showed the gamified exergame improved pulmonary function, nutritional status, and cardiorespiratory fitness. Keywords: Adolescent; overweight; pediatric obesity; respiratory function test; cardiorespiratory fitness.