© 2020, Springer Nature Switzerland AG.Objective: The first aim was to investigate whether there was a mediator role of Internet addiction or uncontrolled/emotional eating on the association between emotion dysregulation and body mass index-standard deviation score (BMI-SDS). The second aim was to detect which of these variables (emotion dysregulation, Internet addiction, and uncontrolled/emotional eating) significantly affect the presence of obesity (OB). Methods: A total of 123 adolescents (OB (n = 65, 57% of girls, mean age = 15 ± 1.9, BMI percentile between 95 and 99) and healthy control (HC) (n = 58; 53% of girls, mean age = 15.5 ± 1.8, BMI percentile between 1 and 84) aged between 11 and 18 were recruited. Difficulties in Emotion Regulation Scale (DERS) and Internet Addiction Test (IAT) were completed by adolescents. Uncontrolled and emotional eating behaviors were measured by Three Factors Eating Questionnaire (TFE-Q)’s sub-domains. Results: There was no significant direct effect of DERS on BMI-SDS, whereas the indirect effect of DERS on BMI-SDS which was mediated by both IAT and TFE-Q was statistically significant. In logistic regression analysis, an increase by 1 point in DERS total score escalated the odds of being OB by 2%. Moreover, a 22-fold increased risk of OB has been detected in moderate/severe Internet addiction compared to no addiction. Conclusion: This cross-sectional study showed that the association between emotion dysregulation and BMI-SDS was totally mediated by internet addiction and uncontrolled/emotional eating. In addition, emotion dysregulation and Internet addiction were significant determinants of OB. A prospective study is needed to detect the causal relationship between these variables. Level of evidence: Level III, case–control analytic study.