Circular RNAs (circRNAs) are a class of RNA molecules generated through back-splicing of precursor mRNAs, characterized by a covalent 3′,5′-phosphodiester bond at the junction site. They are broadly categorized into exonic circRNAs, exonic–intronic circRNAs, and intronic circRNAs. CircRNAs perform diverse biological functions in various diseases, including acting as miRNA sponges, modulating protein synthesis via interactions with RNA-binding proteins (RBPs), directly influencing gene expression, and, in some cases, undergoing translation into proteins. In the cardiovascular system, a plethora of circRNAs has been identified, contributing to pivotal processes involved in cardiovascular development and disease regulation. This chapter will summarize the latest research advancements on the role of circRNAs in cardiovascular diseases, such as pathological cardiac hypertrophy, myocardial infarction, myocardial ischemia-reperfusion injury, dilated cardiomyopathy, and cardiac fibrosis. Additionally, we will explore the potential clinical applications of circRNAs as diagnostic and prognostic biomarkers in cardiovascular diseases.