Abstract: Extracellular vesicles (EVs), as crucial mediators of intercellular communication, participate in the complex regulation of viral infection and host immunity by delivering biomolecules such as proteins, nucleic acids and lipids. This paper systematically reviews the bidirectional mechanisms of EVs in viral infection: On the one hand, viruses hijack the biosynthesis pathways of EVs to package their own components, achieving immune evasion and increasing infectivity. On the other hand, host cells utilize EVs to release antiviral factors or present viral antigens, interfering with the viral life cycle, activating innate immunity, and coordinating adaptive immune responses. Meanwhile, based on advances in single-vesicle analysis, multi-omics technologies and engineered modification strategies, this paper explores the translational potential of EVs in antiviral drug delivery, vaccine development and novel diagnostics, as well as the characteristics and clinical prospects of plant-derived EVs. It also proposes future research directions in response to challenges such as EV heterogeneity, isolation standardization and in vivo targeting.