The present study assessed the effectiveness of individually delivered cognitive behavioral therapy (CBT) interventions in improving depression in patients with breast cancer. A systematic search of Medline (Ovid), PubMed, Cochrane Library, China National Knowledge Infrastructure database, WANFANG, and the VIP database. Quality assessment of included studies was conducted by 2 reviewers independently using the Jadad scale. The pooled effect of the mean difference in the baseline and post-treatment depressive scores was analyzed using different outcome measuring instruments (Self-rating Depression Scale, Hospital Anxiety and Depression Scale, and Hamilton Depression Rating Scale) separately. Thirteen studies involving 966 patients were included. The pooled standardized mean difference (SMD) comparing the intervention groups to the control groups was −0.87 (95% confidence interval [CI], −1.03 to −0.71; overall effect Z, 10.84; P < .0001) in the Self-rating Depression Scale subgroup, which indicated a large effect size based on Cohen's d value (Cohen's d, −0.87). The SMD was −0.50 (95% CI, −0.98 to −0.02; overall effect Z, 20.6; P = .04) in the Hospital Anxiety and Depression Scale subgroup, which indicated a moderate effect size (Cohen's d, −0.50). Finally, the SMD was −2.61 (95% CI, −4.07 to −1.14; overall effect Z, 3.49; P = .0005) in the Hamilton Depression Rating Scale subgroup, which indicated a very large effect size (Cohen's d, −2.61). The overall effect size of the individually delivered CBT in improving depression in breast cancer patients was large. Also, no evidence was found of statistical heterogeneity. The present meta-analysis showed significant efficacy for individually delivered CBT in the reduction of depression in patients after breast cancer surgery. However, further well-designed randomized controlled trials with large sample sizes are needed to provide more valid and reliable results on the long-term outcomes.