Objective: This study aimed to evaluate attachment, emotion regulation, and mindfulness in patients with substance use disorder (SUD) in comparison to a control group (CG). Methods: The study comprised 50 individuals with SUD and 50 healthy people. Addiction Profile Index (API) was applied to the patient group whereas a sociodemographic data form, Mindful Attention Awareness Scale (MAAS), Experiences in Close Relationships Scale (ECRS), Difficulty in Emotion Regulation Scale (DERS) and SCID-5 were applied to both groups. Results: Age, education level, MAAS, ECRS, DERS scores showed statistically significant differences between the groups. Substance use and age, education level, ECRS (avoidant attachment) and DERS were shown to be significant in logistic regression analyses. Age, education level and MAAS demonstrated protective effects, while ECRS (avoidant attachment) and DERS showed weak predictors. MAAS was found to be negatively significant with a weak protective effect and determined that ECRS (anxious attachment) and DERS were positively significant and moderately predictive in the SUD severity. Conclusion: It can be concluded that disordered attachment and emotion dysregulation may have a more pronounced effect on SUD and severity, while mindfulness may have a weaker efficacy with the evaluation of these variables, which may be important in terms of prevention and treatment.