Abstract Background Chronic heart failure and chronic obstructive pulmonary disease (COPD) are both common diseases and often co-exist. Patients with COPD are at increased risk for hospitalizations due to cardiovascular diseases. However, in patients with atrial fibrillation (AF), the relationship between COPD and the risk of heart failure (HF) hospitalization remains unclear. Purpose The purpose of this study was to investigate the relationship between COPD and HF hospitalization in AF patients. Methods The Fushimi AF Registry, a community-based prospective survey, was designed to enroll all of the AF patients in Fushimi-ku, Japan. Fushimi-ku is densely populated with a total population of 283,000 and is assumed to represent a typical urban community in Japan. We started to enroll patients from March 2011, and follow-up data were available for 4,496 patients by the end of February 2022. We compared patients with and without COPD with regard to clinical background and HF hospitalization during follow-up period. Results In this cohort, the proportion of pre-existing HF among patients with COPD was 30.1%, and the proportion of COPD among patients with pre-existing HF was 5.9%. Of 4,496 patients, 238 (5.3%) patients had COPD (COPD; the mean age 75.6 years, female 20.6%), and the remaining 4,258 patients did not (Non-COPD; the mean age 73.5 years, female 41.6%). Patients with COPD were older than those without COPD. However, the proportions of patients with pre-existing HF, previous stroke, vascular disease, cardiomyopathy, coronary artery disease (CAD), diuretic use, renal dysfunction, diabetes mellitus (DM) and hypertension were comparable. During the median follow-up period of 1,824 days, the incidence of HF hospitalization was significantly higher in COPD than in Non-COPD (COPD vs. Non-COPD; 4.85% vs. 3.01% per person-year: p<0.01). In multivariate analysis adjusted by sex, age (≥ 75 years), heart disease (combined by heart failure, vascular disease, cardiomyopathy and CAD), renal dysfunction, DM, hypertension and diuretic use, COPD was an independent risk factor for HF hospitalization (hazard ratio (HR) 1.54, 95% confidence interval (CI) 1.15-2.07, P<0.01) (Figure 1). When we analyzed patients without pre-existing HF, the incidence of HF hospitalization was also significantly higher in COPD than in Non-COPD (COPD vs. Non-COPD; 2.87% vs. 1.75% per person-year: p=0.02). In multivariate analysis after adjusting for the same factors, COPD was an independent risk factor for HF hospitalization (HR 1.63, 95% CI 1.05-2.53, P=0.03) (Figure 2). Conclusion In patients with AF, COPD was the risk of HF hospitalization. The results were consistent in AF patients without pre-existing HF.