The development of dark pro-AIEgens based on solid-state intramolecular motion-caused quenching effect has been rarely reported in biochemical analysis. Herein, an azo-conjugated pro-AIEgen derived from tetraphenylethene is constructed. Owing to the active photoisomerization of the azo bond, it retains a non-emissive property in both solution and solid forms. The obtained pro-AIEgen can be internalized by living cells and undergo reductase-modulated derotation under hypoxia to emit the light. It shows increasing fluorescence when intracellular oxygen concentration becomes lower, making it a potential probe to sense the hypoxic environment. The present probe can also visualize the hypoxic environment created by photodynamic therapy treatment.