Introduction: Although behavioral therapies can effectively treat skin picking disorder (SPD), there is no standardized treatment for improving SPD and its comorbidities and there is no group intervention option. This trial aimed to adapt the Rothbaum trichotillomania protocol to SPD (Study 1) and test its efficacy for treating SPD and comorbidities in individual and group formats (Study 2). Methods: The adapted protocol was applied to 16 SPD patients, who were allocated to group or individual treatment (Study 1). Afterwards, 54 patients were randomly allocated to treatment in an individual (n=27) or group format (n=27) (Study 2). In both studies, assessments of SPD severity, anxiety, depression, clinical status and skin lesion severity were performed at baseline and the endpoint. Results: The adapted protocol was feasible in both treatment modalities (Study 1) and led to high SPD remission rates (individual 63%; group 52%), with no significant difference between intervention types (p = 0.4) (Study 2). SPD, anxiety, and depression symptoms and objective patient lesion measures improved after treatment. There was large effect size for SPD symptom improvement in both treatment types (Cohen’s d: group = 0.88; individual = 1.15) (Study 2). Conclusion: The adapted Rothbaum protocol was effective for SPD remission, comorbidities, and skin lesions, both in individual and group formats. Clinical trial registration: NCT03182478