Extracellular vesicles (EVs) are tiny vesicles released by various cells that contain a variety of proteins, lipids, and nucleic acids, which can have a wide range of effects on other cells. The dynamic composition and contents of EVs can serve as sensitive biomarkers for diagnosing and monitoring various cardiovascular diseases (CVDs). In addition to their diagnostic potential, EVs are therapeutic agents capable of precise modulation and amelioration of CVDs, because of their innate ability to encapsulate and deliver bioactive molecules. This growing field reveals the intricate interplay between EVs and cardiovascular pathophysiology, showing that EVs can act as messengers of intercellular communication for CVD regenerative therapy. Extracellular vesicles serve as dual agents in the field of theranostics, both as diagnostic biomarkers able to decode nuanced molecular signatures of CVDs and as potent vehicles for targeted therapeutic interventions. This review delves into the evolving landscape of EVs, uncovering their diagnostic and therapeutic prospects and emphasizing their growing importance in shaping the future of cardiovascular theranostics.