Dietary polysaccharides, recognised as significant natural bioactive compounds, have demonstrated promising potential for the prevention and treatment of cardiovascular disease (CVD). This review provides an overview of the biological properties and classification of polysaccharides, with particular emphasis on their extraction and purification methods. The paper then explores the diverse mechanisms by which polysaccharides exert their effects in CVD, including their antioxidant activity, protection against ischemia-reperfusion injury, anti-apoptotic properties, protection against diabetic cardiomyopathy, anticoagulant and antithrombotic effects, prevention of ventricular remodeling, and protection against vascular injury. Furthermore, this paper summarises the current status of clinical trials involving polysaccharides in CVD and analyzes the support and challenges posed by these studies for the practical application of polysaccharides. Finally, the major challenges facing the therapeutic use of polysaccharides in CVD are discussed, particularly the issues of low bioavailability and lack of standardized quality control. Through this review, we aimed to provide a reference and guidance for further research on and application of dietary polysaccharides in CVD.