Aims/Background Dapagliflozin is a sodium-glucose cotransporter inhibitor that functions to lower blood sugar by promoting glucose excretion. We conducted a meta-analysis to assess the therapeutic efficacy of dapagliflozin in patients with type 2 diabetes mellitus complicated by coronary heart disease. The objective of this analysis is to provide additional clarity on dapagliflozin's effectiveness in this specific patient population. Methods A systematic review of the literature was performed by searching China National Knowledge Infrastructure (CNKI), Wanfang, Wip Chinese Science, Technology Journals, China Biomedicine, Pubmed, Web of Science, and Cochrane Library. Related literature regarding the effectiveness of dapagliflozin, published since the inception of databases until October 2023, was searched and selected. Subsequent to the screening process, the Jadad scale was used to assess the quality of the gathered literature. The NoteExpress3.2 software (Beijing Aegean Music Technology Co., Ltd., Beijing, China) was utilized to manage the literature. Statistical analysis was conducted using RevMan5.4.1 software (The Cochrane Collaboration, London, UK). The p-value of the Q test determined the heterogeneity of the studies, guiding the choice between fixed or random effect models for establishing the combined effect. Forest plots were used to visualize dapagliflozin's efficacy in treating patients with type 2 diabetes mellitus and coronary heart disease. A funnel plot was plotted to assess potential publication bias. Results Twenty-three studies were eligible for inclusion in this meta-analysis. The results revealed that dapagliflozin has better clinical efficacy (odds ratio [OR] = 3.88, 95% confidence interval [CI] 2.59 to 5.82), left ventricular ejection fraction (LVEF) (OR = 5.43, 95% CI 4.02 to 6.84). The values of left ventricular end-diastolic diameter (LVEDD) and N-terminal pro-brain natriuretic peptide (NT-proBNP) were lower in the experimental group (OR: -4.03 and -84.65, 95% CI -5.08 to -2.98 and -127.05 to -42.25, respectively). In addition, further analysis showed that the experimental group experienced a lower incidence of adverse reactions (OR = 0.30, 95% CI 0.16 to 0.57). Conclusion Dapagliflozin is more effective in controlling type 2 diabetes mellitus complicated by coronary heart disease.