Atrial fibrillation (AF) is associated with mortality, morbidity, and medical costs. Despite the increasing public health importance of AF, race-specific disease distributions and associations between clinical risk factors and AF have received limited attention. This study aimed to compare established associations between risk factors and AF in white Europeans from the UK Biobank and Asian subjects from the Korean NHIS-HEALS (National Health Insurance Service-Health Screening) study. This study included 402,229 and 484,406 patients without a diagnosis of nonvalvular AF from the Korean NHIS-HEALS cohort and UK Biobank, respectively. The incidence of AF, its associations with mortality, common risk factors, biomarkers, prevalent cardiovascular disease, and their attributable risk by race were examined. The median follow-up time was 11.8 years (interquartile range [IQR] 11.1–12.6) in the UK Biobank and 7.6 years (IQR 7.0–8.2) in the Korean NHIS-HEALS. Fewer AF cases were observed in Korean NHIS-HEALS (N=9182; 2.3%) than in the UK Biobank (N=25312; 5.2%). Cardiovascular risk factors, comorbidities, and glucose levels were associated with an increased risk of new-onset AF in both cohorts, with significant interactions by country for associations with body mass index (BMI), economic status, smoking history, history of heart failure, and cholesterol level. BMI was more strongly related to new-onset AF in UK Biobank [hazard ratio (HR), 1.31; 95% confidence interval (CI), 1.29–1.33] compared to Korean NHIS-HEALS (HR, 1.11; 95% CI, 1.09–1.14), with a relative risk ratio of 1.18 (95% CI, 1.15–1.21). Total cholesterol was inversely associated with incident AF in both cohorts (HR, 0.86; 95% CI, 0.85–0.87 versus 0.91; 95% CI, 0.89–0.93 in Korean NHIS-HEALS), relative risk ratio 0.95 (95% CI, 0.92–0.97). Attributable risk proportion of most classical risk factors were similar in both the studies. In this first large-scale comparison of Caucasian and Asian populations, the cumulative risk of developing AF was higher in the UK than in Korea over most of their lifespan. Higher BMI, smoking, history of heart failure, and lower total cholesterol levels were associated with a higher risk of AF in the UK than in Asians.