We applied 24-h Holter monitoring to analyze the characteristics of arrhythmias and heart rate variability in Chinese patients with primary aldosteronism (PA) and compared them with age-, sex-, and blood pressure-matched primary hypertension (PH) patients. A total of 216 PA patients and 261 PH patients were enrolled. The nonstudy data were balanced using propensity score matching (PSM), and the risk variables for developing arrhythmias were then analyzed using logistic regression analysis. Before PSM, the proportion of PA patients with combined atrial premature beats and prolonged QT interval was higher than the corresponding proportion in the PH group. After PSM, the PA group had a larger percentage of transient atrial tachycardia and frequent atrial premature beats, and it had higher heart rate variability metrics. The proportion of unilateral PA combined with multiple ventricular premature beats was higher than that of bilateral PA. Older age, grade 3 hypertension, and hypokalemia were independent risk factors for the emergence of arrhythmias in PA patients. PA patients suffer from a greater prevalence of arrhythmias than well-matched PH patients.