Objective The Acceptance and Action Questionnaire for Obsessions and Compulsions (AAQ-OC) is a version of the Acceptance and Action Questionnaire (AAQ) that specifically measures unwanted intrusive thoughts and responses (e.g., experiential avoidance) to them. This study aimed to investigate the reliability and validity of the Korean version of the AAQ-OC in clinical and nonclinical Korean samples.Methods In this study, 561 university students and 121 patients with obsessive–compulsive disorder (OCD) completed the AAQ-OC and several other psychological scales. Descriptive, correlation, and exploratory and confirmatory factor analyses as well as group comparisons were conducted.Results The results of the exploratory and confirmatory factor analyses indicated a two-factor structure that best fits the data in the university sample: Factors 1 and 2 matched the original Valued Action and Willingness subscales, respectively. The reliability analyses revealed that the AAQ-OC and its factors had excellent internal consistencies. As regards the concurrent validity, the AAQ-OC and its factors had a positive correlation with the AAQ-II and Cognitive Fusion Questionnaire. Compared with the university students, the OCD patients had higher AAQ-OC scores, and their obsessive–compulsive symptoms, particularly the two symptom dimensions of responsibility for harm and mistakes and unacceptable thoughts, were significantly associated with the AAQ-OC and two subscales.Conclusion The findings of this study confirm the reliability and validity of the Korean version of the AAQ-OC.