To explore outcomes of metformin (Met) as an antihyperglycemic agent in patients with type 2 diabetes mellitus (T2DM) combined with chronic heart failure (CHF). This article employed a meta-analysis approach to systematically search several databases. Stata 15.1 software was employed for statistical analysis. This meta-analysis encompassed 15 randomized controlled trials, involving 20,595 patients with T2DM and CHF. The results revealed that in comparison to the non-Met group, the Met group exhibited a significantly reduced risk of all-cause mortality (RR = 0.72, 95%CI: 0.60-0.87) and a notably lower risk of cardiovascular mortality (RR = 0.52, 95%CI:0.29-0.92). However, there was no significant difference in the risk of hospitalization due to heart failure (RR = 0.85, 95%CI: 0.70-1.04). Furthermore, the Met group demonstrated significant improvements in NT-proBNP levels compared to the non-Met group (WMD = -132.91, 95%CI: -173.03, -92.79). Regarding the enhancement of Left Ventricular Ejection Fraction and Left Ventricular End-Diastolic Dimension levels, no statistically significant differences were observed between the two groups. In individuals with T2DM and CHF, the use of Met is linked to a decreased likelihood of all-cause mortality and cardiovascular-related mortality. Furthermore, it can enhance cardiac function in CHF patients without elevating the risk of hospitalization due to heart failure, establishing its safety and potential benefits.