is a gram-negative pathogen that can cause multiple diseases including sepsis, urinary tract infections, and pneumonia. The escalating detections of hypervirulent and antibiotic-resistant isolates are giving rise to growing public concerns. Outer membrane vesicles (OMVs) are spherical vesicles containing bioactive substances including lipopolysaccharides, peptidoglycans, periplasmic and cytoplasmic proteins, and nucleic acids. Emerging studies have reported various roles of OMVs in bacterial virulence, antibiotic resistance, stress adaptation, and host interactions, whereas knowledge on their roles in is currently unclear. In this review, we summarized recent progress on the biogenesis, components, and biological function of OMVs, the impact and action mechanism in virulence, antibiotic resistance, and host immune response. We also deliberated on the potential of OMVs in vaccine development, as diagnostic biomarkers, and as drug nanocarriers. In conclusion, OMVs hold great promise in the prevention and control of infectious diseases, which merits further investigation.