<p>Outer membrane vesicles (OMVs), originating from the outermost membrane of cells, are the extracellular vesicles released by bacteria, containing bacterial outer membrane components such as phospholipids, lipopolysaccharides (LPS), outer membrane proteins, and bacteria-specific antigens. OMVs have progressively been acknowledged as a novel secretory system, playing a pivotal role in mediating bacterial infections and modulating host immune responses. They are anticipated to emerge as a promising therapeutic target for the intervention of bacterial infectious diseases in the future. Based on this, the present article provides a comprehensive review of the role of OMVs in bacterial infections and immune modulation. This article summarizes that OMVs can mediate bacterial infections by transporting virulence genes and antibiotic resistance genes, as well as by carrying pathogen-associated molecular patterns (PAMPs). Additionally, they modulate host immune functions through direct interactions with immune cells such as neutrophils, macrophages, and dendritic cells. Furthermore, OMVs can facilitate bacterial immune evasion by modulating biofilm formation, resisting host antimicrobial peptides, and inhibiting the functionality of the complement system. Given that OMVs are non-replicative and contain a wealth of bacterial antigens, coupled with their ability to effectively activate the immune system, they are regarded as highly promising vaccine candidates. This article concludes by summarizing the concepts and strategies for developing vaccines based on OMVs. It is anticipated that this article will provide a more comprehensive understanding of the role of OMVs in research related to bacterial infectious diseases.</p>