Dendritic cell (DC)-derived small extracellular vesicles (DEVs) are recognized as a highly promising alternative to DC vaccines; however, the clinical testing of DEV-based immunotherapy has shown limited therapeutic efficacy. Herein, we develop a straightforward strategy in which DCs serve as a cell reactor to exocytose high-efficient DEV-mimicking aggregation-induced emission (AIE) nanoparticles (DEV-AIE NPs) at a scaled-up yield for synergistic photodynamic immunotherapy. Exocytosed DEV-AIE NPs inherit not only the immune-modulation proteins from parental DCs, enabling T cell activation, but also the loaded AIE-photosensitizer MBPN-TCyP, inducing superior immunogenic cell death (ICD) by selectively accumulating in the mitochondria of tumor cells. Eventually, DEV-AIE synergistic photodynamic immunotherapy elicits dramatic immune responses and efficient eradication of primary tumors, distant tumors, and tumor metastases. In addition, cancer stem cells (CSCs) in 4T1 and CT26 solid tumors were significantly inhibited by the immune functional DEV-AIE NPs. Our work presents a facile method for the cellular generation of EV-biomimetic NPs and demonstrates that the integration of DEVs and AIE photosensitizers is a powerful direction for the production of clinical anticancer nanovaccines.