The effect size of psychological counseling based on the Cognitive Behavioral Therapy (CBT) approach on depression and anxiety, was conducted using a meta-analysis method. According to the defined criteria, eight primary studies on anxiety and 21 on depression are included in the meta-analysis. The effect sizes based on a random-effects model are also determined. The mean effect size was -0.936 (95% CI [-1.215, -0.657]) for anxiety and -0.844 (95% CI [-1.065, - 0.624]) for depression. Accordingly, CBT can have a large effect on reducing the level of depression and anxiety in participants. As a result of the moderator analysis, the effect sizes relating to depression did not significantly differ according to the type of test and experimental design. The number of sessions was a non-significant predictor of depression, but the experimental group size was a significant predictor of CBT's effect size on depression. As for the moderator analysis in the anxiety variable, the effect sizes relating to anxiety did not significantly differ by age group, types of publication, counseling, experimental design, test, and anxiety. Also, the number of sessions and experimental group size were not significant predictors of anxiety. According to these results, CBT is effective in reducing the depression and anxiety levels of individuals.