Sentinel lymph node (SLN) detection is of great significance for the prevention and treatment of cancer metastasis. Herein, we introduce silicon nanoparticles (SiNPs)-based exosome (SiNPs@EXO) probes for distinguishing normal and metastatic SLNs. Typically, SiNPs are suitable for stable and long-term tracking of exosomes, while cancer cell-driven exosomes with a tumor-homing effect allow targeting metastatic SLNs. Remarkably, the as-fabricated SiNPs@EXO has the ability to label metastatic SLNs, i.e., the fluorescence signal in SLNs reaches the peak within 0.5 h and remains up to 3 h. Comparatively, SLN tracers (e.g., indocyanine green) used clinically can illuminate SLNs 1 h post injection, whereas the signal witnesses a sharp fall then. Moreover, evaluations based on preclinical data confirm the negligible side effects of the SiNPs@EXO. Our results provide new tools for targeting SLNs and predicting lymphatic metastasis of tumor.