Recent advances in nanoscale engineering have created a new class of particulate bionanotechnology that uses biomimicry to better integrate vaccine adjuvants and antigens. These pathogen-like particles, or PLPs, can come from a variety of sources, ranging from fully synthetic platforms to biologically-derived, self-assembling systems. Outer membrane vesicles (OMVs) derived from gram-negative bacteria hold great promise as a next-generation vaccine platform. OMVs have the potential to seamlessly combine the biomimicry of virus-like particles with flexible, heterologous antigen integration and broad bacterial self-adjuvanticity. By employing molecularly engineered targeting and stimulation of key immune cells, we have pioneered the development of recombinant OMVs as a vaccine delivery platform and used the resulting engineered OMVs against high-impact, unsolved vaccine targets including bacterial pathogens, viruses, and human cancers.