Abstract Background Patients with coronary heart disease (CHD) diagnoses often experience impacts on patient-reported outcomes (quality of life, depression, disease self-management and self-efficacy) at a time when secondary prevention is required. Peer support has proven benefits for these issues in many chronic conditions but synthesis of the evidence in CHD populations has not been undertaken. Purpose In this systematic review and meta-analysis, we aimed to explore the impact of peer support interventions on health-related quality of life, depression, anxiety, self-management and self-efficacy in CHD. Methods Electronic databases were searched from inception to November 2023 (MEDLINE, Embase, PsycINFO, CINAHL, Scopus, PubMed [non-MEDLINE], Web of Science, and the Cochrane Central Register of Controlled Trials). Randomised controlled trials (RCTs) evaluating peer support interventions (that enable experience sharing and/or support by others with the same condition) in populations with diagnosed CHD were eligible for inclusion. Risk of bias was assessed using the Cochrane risk of bias tool. Meta-analyses were undertaken in RevMan Version: 7.4.0 using the inverse variance method and a random effects model. Results In total, 16 papers reporting 14 unique RCTs were included. The total sample (n=1793) was 65% male with a mean age of 54.5±13.0 years. The diagnosis of the samples varied between studies, including coronary artery bypass graft(s), first time or newly diagnosed myocardial infarction and percutaneous coronary intervention. By 6-months follow-up, peer support interventions demonstrated no statistically significant improvements in health-related quality of life (SMD -0.38, 95% CI -1.84, 1.08), depression (SMD -0.09, 95% CI -0.26, 0.08) and anxiety (SMD -0.85, 95% CI -1.83, 0.14). Whereas, improvements occurred in disease self-management (SMD 1.49, 95% CI 0.66, 2.32) and self-efficacy in both short term (by 6-months, SMD 0.57, 95% CI 0.37, 0.77) and longer term (6-12 months, SMD 0.67, 95% CI 0.29, 1.05). Peer support interventions varied widely in format and several studies were of poor quality. Conclusion Peer support interventions benefit patient-reported outcomes of disease self-management and self-efficacy up to 6 and 12 months, but not for other patient reported outcomes after CHD diagnosis. More exploration is needed of content, delivery and focus of peer support interventions to maximise effectiveness for CHD secondary prevention.