Metabolic glycoengineering of unnatural glycans with bio-orthogonal chemical groups and a subsequent click reaction with fluorescent probes have been widely used in monitoring various bioprocesses. Herein, we developed a dual-responsive metabolic precursor that could specifically generate unnatural glycans with azide groups on the membrane of targeted cancer cells with high selectivity. Moreover, a water-soluble fluorescent light-up probe with aggregation-induced emission (AIE) was synthesized, which turned its fluorescence on upon a click reaction with azide groups on the cancer cell surface, enabling special cancer cell imaging with low background signal. Furthermore, the probe can generate 1O2 upon light irradiation, fulfilling its dual role as an imaging and therapeutic agent for cancer cells. Therefore, the concepts of the cancer-cell-specific metabolic precursor cRGD-S-Ac3ManNAz and the AIE light-up probe are promising in bio-orthogonal labeling and cancer-specific imaging and therapy.