Background Body dysmorphic disorder (BDD) is the most distressing body image disorders. The aim of this study was to evaluate the efficacy of acceptance and commitment therapy (ACT) in improving psychological problems in individuals with BDD symptoms. Methods This was a randomized clinical trial study with 34 eligible patients with BDD symptoms were recruited from Kashan city in 2021. These individuals were randomly assigned to either an intervention group (n = 17) with 8 weekly ACT sessions or a placebo group (n = 17). Used assessments included Yale-Brown Obsessive-Compulsive Scale Modified for Body Dysmorphic Disorder (Y-BOCS-BDD), Depression Anxiety Stress Scales 21-item version (DASS-21), Cognitive Fusion Questionnaire (CFQ), and Body-Image Acceptance and Action Questionnaire (BI-AAQ). Data were analyzed by using SPSS 26. Results The results revealed that there was no significant difference in demographic variables of either age or gender. On the other hand, statistical analyze showed that two groups had the significant difference in term of body symptoms severity (F = 4.89), cognitive fusion (F = 9.18), emotional symptoms (depression F = 4.03, anxiety F = 4.02, and stress F = 4.87) in the post-test. Conclusion It can be said ACT has a positive effect on body image flexibility, cognitive fusion, and emotional symptoms of young people with body dysmorphic disorders and it can improve their symptoms.