<p>Religious Rational Emotive Behavior Therapy (RREBT) has emerged as an important innovation addressing the global demand for culturally and spiritually sensitive counseling interventions. While Rational Emotive Behavior Therapy (REBT) is empirically established in restructuring irrational beliefs, its secular orientation has raised concerns regarding its relevance and acceptability among religiously committed populations. This underscores the need for a systematic consolidation of evidence on how RREBT has been adapted and applied across diverse faith traditions. The present study aimed to systematically review and synthesise findings on the adaptation, reported impacts, methodological limitations, and ethical challenges of RREBT. Following PRISMA guidelines, systematic searches were conducted in Scopus, PubMed, and Google Scholar, resulting in 4351 initial records. After rigorous screening and quality appraisal using the Mixed Methods Appraisal Tool (MMAT), 27 eligible studies published between 1995 and August 2025 were synthesised through thematic analysis. The review identified three major themes: first, the adaptation and application of RREBT across Christian, Islamic, Jewish, LDS, and Buddhist contexts, which enhanced therapeutic alliance through cultural resonance; second, consistent positive impacts on clinical, behavioral, and spiritual outcomes, including reductions in depression, anxiety, trauma, and improvements in discipline, motivation, and resilience; and third, methodological and ethical challenges such as small sample sizes, limited randomized trials, lack of fidelity protocols, and risks of proselytisation or theological distortion. Overall, the findings affirm RREBT’s promise as a culturally congruent therapeutic model, while highlighting the need for more rigorous and ethically grounded research to establish it as an evidence-based framework in psychotherapy.</p>