Objective: Peer support is a common form of social support that is provided by individuals with the same disease, which is cost-effective and has enhanced health outcomes for patients. This study aimed to determine the effectiveness of peer support interventions on quality of life (QOL), depression, anxiety, and self-efficacy among patients with cancer.Methods: A systematic search of seven databases were conducted from inception to January 2021. Studies were screened and assessed by two independent reviewers. Data synthesis was conducted using RevMan 5.3 software, and the standardized mean difference was used to calculate pooled effect sizes.Results: Seventeen studies were included in current review. The meta-analysis indicated significant beneficial effects of peer support on QOL (SMD = 0.48, 95% CI 0.21-0.75; p < 0.001), depression (SMD =-0.23, 95% CI-0.39 to-0.07; p = 0.005), anxiety (SMD =-0.24, 95% CI-0.45 to 0.03; p = 0.03), and self-efficacy (SMD = 0.22, 95% CI 0.03-0.42; p = 0.03) relative to controls. The subgroup analysis for QOL revealed that peer support delivered in the mixed mode contributed more than peer support delivered in the single mode (e.g., face-to-face or telephone).Conclusion: Peer support has significant effects on improving QOL and self-efficacy as well as alleviating depression and anxiety among patients with cancer. Additional randomized controlled trials with rigorous design and larger sample sizes are warranted in the future. Practice implications: Peer support programs might benefit patients with cancer and could be used as a comple-mentary approach to traditional healthcare services during cancer rehabilitation.