Background::The clinical characteristics of patients with the comorbidities of hypertension and coronary artery disease (HT-CAD) and atrial fibrillation (AF) are largely unknown. This study aimed to investigate the prevalence of AF in patients with HT-CAD and clinical characteristics of patients with both HT-CAD and AF.Methods::This cross-sectional study was conducted in Chinese People’s Liberation Army General Hospital in Beijing, China, and included 20,747 inpatients with HT-CAD with or without AF from August 2008 to July 2018. We examined the overall prevalence, clinical characteristics, comorbidity profiles, treatment patterns, and blood pressure (BP) control of patients with both HT-CAD and AF. Multivariate logistic regression was used to investigate the associations of cardiovascular risk factors with AF in patients with HT-CAD.Results::The overall prevalence of AF in patients with HT-CAD was 4.87% (1011/20,747), and this increased with age; to be specific, the prevalence in women and men increased from 0.78% (2/255) and 1.02% (26/2561) at the age of <50 years to 8.73% (193/2210) and 10.28 % (298/2900) at the age of ≥70 years, respectively. HT-CAD patients who had AF had a higher prevalence of cardiovascular-related comorbidities than those without AF. Multivariate logistic regression showed that age, gender (male), body mass index, heart failure, and chronic kidney disease were independently associated with the risk of AF in patients with HT-CAD. For those with both HT-CAD and AF, 73.49% (743/1011) had a CHA 2DS 2-VASc score of ≥4, and only about half of them had the BP controlled at <140/90 mmHg, which indicated a high risk of thromboembolism and stroke. The use of oral anticoagulation increased during the study period (10.00% [20/200] in 2008 to 2011 vs. 30.06% [159/529] in 2015 to 2018, P < 0.01), but remained at a relatively low level. Conclusions::AF is highly prevalent among patients with HT-CAD. Patients with both HT-CAD and AF have a higher prevalence of cardiovascular-related comorbidities, lower BP control rate, and lower use of oral anticoagulation.