The construction of open hot-spot structures that facilitate the entry of analytes is crucial for surface-enhanced Raman spectroscopy. Here, metallic niobium nitride (NbN) three-dimensional (3D) hierarchical networks with open nanocavity structure are first found to exhibit a strong visible-light localized surface plasmon resonance (LSPR) effect and extraordinary surface-enhanced Raman scattering (SERS) performance. The unique nanocavity structure allows easy entry of molecules, promoting the utilization of electromagnetic hot spots. The NbN substrate has a lowest detection limit of 1.0 × 10-12 M and a Raman enhancement factor (EF) of 1.4 × 108 for contaminants. Furthermore, the NbN hierarchical networks possess outstanding environmental durability, high signal reproducibility, and detection universality. The remarkable SERS sensitivity of the NbN substrate can be attributed to the joint effect of LSPR and interfacial charge transport (CT).