Hierarchical CoNiO2 polyhedral mesoporous structure using a novel hydrothermal method followed by the microwave carbon bath irradiation annealing process. The nanostructure, morphology, surface area and magnetic properties are characterized and investigated in detail. These results reveal that the regular hexagon mesoporous structures and the large specific surface area of 53.57 m3/g play an essential role in enhanced electrochemical activity. CoNiO2 modified glass carbon electrode with output power of 720 W (CNO-720/GCE) exhibits perfect electrochemical ultratrace detection toward Cu(II) with low detection limit of 3.1 nM and high sensitivity of 7.554 μA/μM under the optimized experimental conditions, and also shows the excellent repeatability, reproducibility, stability and selectivity. The improved electrochemical performance is associated with the specific hierarchical polyhedral structure, abundant mesporous channels, stable crystal surface and strong affinity toward Cu(II). Therefore, the synthesized CNO-720/GCE nanomaterials can be applied for ultratrace detection of heavy metal ions.