we developed a multifunctional AIEgen light-upprobe, BCN-TPET-TEG, for fluorescence turn-on bio-orthogonallabeling of tumor in vivo and for image-guided therapy. BCNTPET-TEG is composed of an AIE PS core, copper-free clickableBCN and hydrophilic TEG. It has a broad absorption spectrum invisible region with bright NIR emission in solid state and a high1O2 generation quantum yield of 59.1%. Due to the hydrophilicityof TEG and its AIE-active character, BCN-TPET-TEG was weaklyemissive in aqueous media and its fluorescence could hardlychange upon incubation with different biomolecules to ensure alow background signal. Upon bio-orthogonal reaction with theexpressed azide on tumor cells, the fluorescence of BCN-TPETTEGwas significantly enhanced due to the restriction of molecularmotions. The bio-orthogonal labeling of tumor by this “turn-on”probe could achieve rapid tumor-specific imaging and real-timemonitoring of the amount of covalently labeled BCN-TPET-TEGonto tumor. This is significantly advantageous as compared to thecommercial “always-on” probe, DBCO-Cy5, which requires bodyclearance before the tumor signal could be identified.