Objective Rational emotive behavior therapy (REBT) model of psychological health assumes that rational beliefs cause functional emotions and adaptive behavior, but the presumed role of rational beliefs as protective factor against psychological distress/disorders is still in debate. An important step in validating an evidence-based therapy is to investigate the underling theoretical assumptions. Thus, the aim of the present meta-analysis is to investigate the direction and magnitude of the relationship between rational beliefs and psychological distress. Method Our search identified 26 studies that met our criteria. We evaluated the effect size using the random-effects model and we tested the moderator role of several variables. Results The overall results revealed a medium negative association between rational beliefs and psychological distress, r = −0.31. The strongest association was found for unconditional acceptance beliefs (r = −0.41). Conclusion The results add empirical evidence for the underling theory of REBT and revealed that the strength of the association between rational beliefs and distress is robust for a wide range of emotional problems. Therefore, rational beliefs could be a trans-diagnostic protective factor against distress. Moreover, results emphasized that rational beliefs type is an important factor, suggesting an increased focus in therapy on the developing of unconditional acceptance and self-acceptance beliefs.