This study aimed to elucidate a potential dose-dependent relation between coffee intake and atrial fibrillation (AF) incidence in a multi-ethnic setting. Previous studies were comprised mainly of White populations, and an exploration of dose dependency is limited. To address these gaps, we analyzed the Multi-Ethnic Study of Atherosclerosis data, a prospective cohort study. In the primary analysis, we crudely divided patients into 3 groups: nonconsumers, 1 to 3 cups/month, and ≥1 cup/week. For the secondary analysis, we stratified the cohort into 9 groups of gradual increments for coffee consumption. A multivariable cox proportional hazards regression model was adjusted for 6 potential confounders: age, gender, smoking, hypertension, diabetes mellitus, and alcohol. Subjects who drank ≥1 cup of coffee/week had a higher incidence of AF (adjusted hazard ratio 1.40, p = 0.015) than nonconsumers. Furthermore, in the secondary analysis, there was an overall trend, albeit not consistent, of increasing adjusted hazard ratio with progressively increasing doses of coffee in the following groups: 1 to 3 cups/month, 2 to 4 cups/week, 2 to 3 cups/day and ≥6 cups/day. Notably, AF incidence was highest (9.8%) for the group consuming the most coffee, that is, ≥6 cups/day (p = 0.02). Stratification by race/ethnicity suggested the results may be driven by White and Hispanic rather than Black or Chinese-American subgroups. In conclusion, the findings suggest an association between coffee consumption and incident AF in contrast to most previous studies.