Background: In the past decade, multiple studies have examined the effectiveness of Acceptance and Commitment Therapy (ACT) for substance use disorders relative to other active treatments. The current meta-analysis examined the aggregate effect size when comparing ACT to other treatments (e.g., CBT, pharmacotherapy, 12-step, treatment as usual) specifically on substance use outcomes. Method: A total of 10 randomized controlled trials were identified through systematic searches. Results: A significant small to medium effect size was found favoring ACT relative to active treatment comparisons following treatment. Effect sizes were comparable across studies for smoking cessation (k = 5) and for other drug use disorders (k = 5). Conclusions: Based on these findings, ACT appears to be a promising intervention for substance use disorders. Limitations and future directions are discussed.