Introduction: The current study aims to evaluate if and to what extent mindfulness-based interventions (MBIs) could promote an incremental effectiveness compared to interventions usually provided in clinical practice to treat Alcohol and Drugs Use Disorders. In line with this aim, we accomplished a meta-analytic review of randomized and nonrandomized controlled trials, considering primary and secondary outcomes that comprehensively operationalize treatment efficacy. Methods: We conducted the online research up to August 31st 2017. Adequate procedures for Cohen’s d computation were applied. Heterogeneity indexes, moderators, bias of publication, and Orwin’s fail-safe number were also estimated. Results: Thirty-seven studies were included (n = 3,531 patients). We observed null effect sizes for attrition rate and overall mental health. Small effect sizes were detected in abstinence, levels of perceived stress, and avoidance coping strategies. Moderate effect sizes were revealed in anxiety and depressive symptoms. Large effect sizes were associated to levels of perceived craving, negative affectivity, and post-traumatic symptoms. Conclusion: MBIs seemed to show clinically significant advantages compared to other clinical approaches in relation to specific primary and secondary outcomes. Conversely, treatment retention was independent of the therapeutic approach.