Sensitive and stable triethylamine (TEA) gas sensors are desirable for environmental and human safety. However, the high operating temperature of the metal-oxide-based gas sensors poses a limitation on their wide applications. Herein, we fabricate an exceptional TEA gas sensor based on the core-shell heterostructure comprising crystalline CuO and amorphous InO/ZnO (CuInZnO) via a facile electrodeposition method. Remarkably, the optimum gas sensor (CuInZnO-3) exhibits an outstanding gas response (∼25) toward a 10 ppm TEA at room temperature. Moreover, CuInZnO-3 shows excellent selectivity, linear response, and stability. The superior sensing performance can be mainly ascribed to the unique core-shell nanorod heterostructure with a high specific surface area, allowing the formation of p-n junctions. The amorphous nature of the InO/ZnO shell also enriches the active oxygen on the surface and enhances gas adsorption.