The present article studied gas sensor sensing characteristics based on surface-modified porous silicon (PS) by depositing the metal oxide semiconductor layer. The PS layer was prepared through the electrochemical etching of crystalline silicon in an HF-based solution. DC magnetron sputtering technology was used to obtain the p-CuO layer on the surface of the p-PS. The obtained material’s structural, morphological, and sensing behavior were investigated using SEM, XRD, Raman spectra, and the current–voltage characteristics. For the detection of toluene and chloroform vapors, a planar structure was used. The sensing response value revealed that the CuO/PS-based gas sensors have good sensitivity for toluene and chloroform vapors. The sensing mechanism is explained using schematic energy band diagrams. Therefore, this approach is helpful for the development of a simple, cost-effective sensor for detecting non-polar chemical analytes.