<p>As demonstrated, heart rate variability (HRV) biofeedback (HRVB) is effective in managing chronic conditions. However, reviews specifically addressing HRVB effects on cardiac autonomic dysfunction in patients with cardiovascular diseases (CVDs) are lacking. We evaluated HRVB effects on autonomic, hemodynamic, and psychological outcomes in such patients. This systematic review and meta-analysis of randomized controlled trials (RCTs) searched MEDLINE, CINAHL, Web of Science, Cochrane Central Register of Controlled Trials, and Igaku Chuo Zasshi from inception to April 2025. We included RCTs on HRVB in CVD populations and excluded those without HRV, clinical, or psychological outcomes. Two reviewers independently screened, extracted data, and assessed risk of bias using Cochrane RoB 2 tool. Random-effects models were applied to HRV indices, blood pressure, respiratory rate, and psychological outcomes. From 2402 records, 13 RCTs (965 participants; 795 analyzed) were included. HRVB significantly improved the standard deviation of NN interval; low-frequency (LF) and logLF increased, high-frequency (HF) and logHF showed no significant changes. Both systolic (mean difference [MD] =  − 3.08, 95% confidence interval [CI] − 4.77 to − 1.38) and diastolic (MD =  − 3.23, 95% CI − 4.69 to − 1.78) blood pressure decreased. Respiratory rate showed no significant changes. Depression (five RCTs) and anxiety (two RCTs) showed no significant improvement. Most studies were rated as having concerns or high risk of bias. The HRVB may modestly enhance autonomic activity and reduce blood pressure in patients with CVD; however, its effects on parasympathetic activity and psychological outcomes remain inconclusive. Further large-scale, rigorously designed trials are required to establish their clinical utility.</p><p><?qj left?><?noindent??> <i>Registration</i>: PROSPERO; CRD420251030160.</p>