Bacterial extracellular vesicles (BEVs) are nanoscale membranous structures secreted by both Gram-negative and Gram-positive bacteria throughout all growth phases and under various environmental conditions. These vesicles, which include outer membrane vesicles (OMVs), membrane vesicles (MVs), and other subtypes, are involved in intercellular communication, macromolecule exchange, and stress adaptation. Originally studied for their role in biofilm formation and toxin delivery, BEVs are now recognized for their complex functions, including horizontal gene transfer, immune modulation, and contribution to pathogenicity. Unlike eukaryotic and archaeal vesicles, which utilize mechanisms such as endosomal sorting complexes required for transport, bacterial vesiculation processes are distinct, highly regulated, and species-specific. Recent advancements have shifted the focus toward the biotechnological and medical potential of BEVs, with research highlighting their application in drug delivery, vaccine development, biosensing, and bioremediation. Given their ability to encapsulate and protect bioactive molecules, as well as their natural roles in host–microbe interactions, BEVs represent promising platforms for next-generation therapeutics and diagnostics. This chapter provides an updated overview of BEV biogenesis, composition, and emerging applications, reinforcing their relevance as multifunctional tools in biotechnology and medicine.