Cognitive-behavioral therapy (CBT) is considered an evidence-based psychological intervention for various mental disorders. However, mental health clinicians should be cognizant of the population that was used to validate the intervention and assess its acceptability to a target group that is culturally different. We systematically reviewed published empirical studies of CBT adapted for religious individuals with mental disorder to determine the extent to which religiously modified CBT can be considered an empirically supported treatment following the criteria delineated by the American Psychological Association Task Force on Promotion and Dissemination of Psychological Procedures. Overall, nine randomized controlled trials and one quasi-experimental study were included that compared the effectiveness of religiously modified CBT to standard CBT or other treatment modalities for the treatment of depressive disorders, generalized anxiety disorder, and schizophrenia. The majority of these studies either found no difference in effectiveness between religiously modified CBT compared to standard CBT or other treatment modalities, or early effects that were not sustained. Considering the methodological limitations of the reviewed studies, religiously modified CBT cannot be considered a well-established psychological intervention for the treatment of the foregoing mental disorders following the a priori set criteria at this juncture. Nevertheless, melding religious content with CBT may be an acceptable treatment modality for individuals with strong religious convictions.