This study aimed to assess atrial fibrillation (AF) incidence and predictive factors in hypertensive patients and to formulate an AF risk assessment score that can be used to identify the patients most likely to develop AF. This was a cohort study of patients recruited in primary healthcare centers. Patients aged 40 years or older with hypertension, free of AF and with no previous cardiovascular events were included. Patients attended annual visits according to clinical practice until the end of study or onset of AF. The association between AF incidence and explanatory variables (age, sex, body mass index, medical history and other) was analyzed. Finally, 12,206 patients were included (52.6% men, and mean age was 64.9 years); the mean follow-up was 36.7 months, and 394 (3.2%) patients were diagnosed with AF. The incidence of AF was 10.5/1000 person-years. Age (hazard ratio [HR] 1.06 per year; 95% confidence interval [CI] 1.05-1.08), male sex (HR 1.88; 95% CI 1.53-2.31), obesity (HR 2.57; 95% CI 1.70-3.90), and heart failure (HR 2.44; 95% CI 1.45-4.11) were independent predictors (p < 0.001). We propose a risk score based on significant predictors, which enables the identification of people with hypertension who are at the greatest risk of AF.