Epicardial adipose tissue (EAT) is the adipose tissue located between the myocardium and the visceral layer of the epicardium. There is no muscular fascia between it and the myocardium, allowing for mutual influence through microcirculation. Its pathophysiological function in cardiovascular diseases has attracted widespread clinical attention. EAT can exert protective effects on adjacent myocardium either by uptaking fatty acids and secreting anti-inflammatory factors, or conversely, contribute to cardiovascular diseases by secreting inflammatory factors and through fatty acid infiltration. Detection of EAT can enable early diagnosis and risk assessment of cardiovascular diseases. Furthermore, EAT represents a promising therapeutic target; Clinically, improving the quality and function of EAT may offer a strategy for treating cardiovascular diseases. This article reviews current research on the physiological basis of EAT, the mechanisms underlying its transition from physiological to pathological functions, its role in cardiovascular diseases, methods for assessing EAT, and approaches for targeting EAT to treat cardiovascular diseases, with the aim of systematically illustrating the potential role of EAT in the prevention and treatment of cardiovascular diseases.