Cardiovascular diseases stand as a leading cause of death worldwide, incurring substantial medical costs and care. Despite significant advancements in diagnosing and treating these conditions, their mortality rate remains high, emphasizing the urgent need for novel diagnostic and therapeutic strategies for early detection and effective treatment. Magnetic nanoparticles (MNPs) have recently garnered increasing attention as potential candidates for enhancing the efficacy of CVD detection and treatment. MNPs, along with their composites or hybrid biomaterials, offer new approaches for CVD targeting, enabling precise localization to the heart or blood vessels, and reducing drug toxicity. Additionally, remarkable outcomes have been achieved using MNPs in diagnosing blood vessel and heart diseases. This review provides a comprehensive overview of various types of MNPs, their characteristics, and synthesis methods. Subsequently, it delves into the leading applications of MNPs in cardiovascular diseases, encompassing diagnostic, therapeutic, and theranostic applications.