Abstract Aims Sodium-glucose cotransporter-2 inhibitors (SGLT2is) have been shown to improve cardiovascular outcomes and reduce the incidence of atrial fibrillation (AF) in patients with type 2 diabetes mellitus (T2DM). We investigated the clinical outcomes with and without the use of SGLT2is in patients with T2DM and concomitant AF. Methods and results We derived patient data from a clinical data warehouse constructed from the electronic medical records of seven medical centres. Data for 11 012 patients diagnosed with both AF and T2DM were analysed. New SGLT2i users were classified into the SGLT2i group and those who were not prescribed SGLT2is were classified into the control group. We performed a 1:2 propensity score (PS)-matching analysis. The primary endpoint was a composite of all-cause death or hospitalization due to heart failure (HF) events in 3 years. The PS-matched population consisted of 1115 patients in the SGLT2i group and 2050 patients in the control group. Incidence of the primary endpoint was significantly lower in the SGLT2i group [8.4 vs. 14.6%, hazard ratio (HR) 0.69, 95% confidence interval (CI) 0.55–0.87]. Sodium-glucose cotransporter-2 inhibitors use was associated with significantly lower all-cause mortality (HR 0.43, 95% CI 0.29–0.67) and HF hospitalization (HR 0.77, 95% CI 0.59–0.99). Adverse renal events, defined as >50% increase in serum creatinine level or initiation of dialysis, occurred less often in the SGLT2i group (HR 0.50, 95% CI 0.38–0.66, P < 0.001). Conclusion Use of SGLT2is in patients with T2DM and concomitant AF was associated with reduced mortality or HF hospitalization events.