A rapid and sensitive detection platform for GSH has been constructed by combining a MnO₂ nanosheet with a luminescent iridium(III) complex [Ir(Cl-phq)₂(Cl-phen)]⁺. The MnO₂ nanosheet was prepared by using a facile one-step approach and was characterized by TEM. The luminescence intensity of the detection platform responded linearly with the GSH concentration from 1 to 200 μM (R² = 0.9951), and the detection limit for GSH was 0.13 μM. More importantly, practical application of the detection platform for visualizing the intracellular GSH distribution in living zebrafish has also been demonstrated.