Mesenchymal stem cell (MSC) therapy is a frequently used treatment option for achieving a better prognosis in patients with heart failure (HF). However, due to reported adverse effects, patients are often hesitant to consider this treatment. Consequently, the aim of this systemic review and meta-analysis is to further investigate the effects of MSCs on survival outcomes, hospital readmissions, and left ventricular ejection fraction (LVEF) in individuals with pre-existing HF. We systematically searched PubMed, Web of Science, Embase, and Cochrane Library to review studies published up until July 16, 2023. Risk ratios were generated using the extracted data for all the outcomes except LVEF. The mean difference was generated for LVEF. Sensitivity analysis was performed to investigate heterogeneity, and the risk of bias tool was used to assess the quality of the included studies. Fourteen randomized controlled trials were included in the meta-analysis. Pooled results revealed that the MSC therapy group did not significantly affect the outcomes of cardiovascular death, rehospitalization rate, myocardial infarction, recurrence of HF, and total death when compared to a control group. However, MSC therapy was significantly associated with an increased LVEF (RR = 3.35; 95% CI: 0.79-5.72; p = 0.010; I2 = 95%). Upon sensitivity analysis, MSC therapy was significantly associated with a decreased hospitalization rate (RR = 0.46; 95% CI: 0.34-0.64; p < 0.00001; I2 = 0%). MSC transplantation results in a significantly improved LVEF and rehospitalization rate.