Organic ligand‐protected metal nanoclusters have attracted extensively attention owing to their atomically precise composition, determined atom‐packing structure and the fascinating properties and promising applications. To date, most research has been focused on thiol‐stabilized gold and silver nanoclusters and their single crystal structures. Here the single crystal copper nanocluster species (Cu₆(SC₇H₄NO)₆) determined by X‐ray crystallography and mass spectrometry is presented. The hexanuclear copper core is a distorted octahedron surrounded by six mercaptobenzoxazole ligands as protecting units through a simple bridging bonding motif. Density functional theory (DFT) calculations provide insight into the electronic structure and show the cluster can be viewed as an open‐shell nanocluster. The UV–vis spectra are analyzed using time‐dependent DFT and illustrates high‐intensity transitions involving primarily ligand states. Furthermore, the as‐synthesized copper clusters can serve as promising nonenzymatic sensing materials for high sensitive and selective detection of H₂O₂.