Abstract: Plant cells, bacterial cells, and mammalian cells can produce and secret extracellular vesicles (EVs) encapsulated with proteins, nucleic acids, lipids, and small molecules. At the very beginning of research on EV, EVs were thought to function solely as a way to dispose cellular waste. Later on, EVs were found to be able to carry and transfer bioactive substances between cells and change the phenotype of the recipient cells. More and more studies have confirmed that EVs are novel mediators for short- and long-range intercellular communication and new pattern of intercellular communication. EVs have broad physiological and pathological effects and can serve as diagnostic biomarkers, drugs, drug targets, and drug carriers. In this paper, we review the effect, application, and engineering strategies of EVs from different sources in targeted cancer therapy.