Drug-induced liver injury (DILI) is a common clinical problem with urgent respect to demanding early diagnosis. Exosomal miRNAs are reliable and noninvasive biomarkers for the early diagnosis of DILI. However, accurate and feasible detection of exosomal miRNAs is often hampered by the low abundance of miRNAs, inefficient exosome separation techniques, and the requirement for RNA extraction from large sample volumes. Here, the multifunctional magnetic vesicles are constructed by loading a multiple signal amplification detection system and magnetic nanoparticles into virus-mimicking engineered vesicles to achieve in situ analysis of hepatogenic exosomal miRNAs, which do not require miRNA extraction or target amplification. Virus-mimicking engineered vesicles carrying large surface proteins of hepatitis B virus are designed to achieve the specific identity and fusion of hepatogenic exosomes, and the multiple signal amplification detection system assembled by catalytic hairpin assembly technology and CRISPR/Cas13a technology can achieve highly sensitive in situ detection of miRNAs in exosomes with a low limit of detection (LOD) of 1.25 × 10