Crystalline silicon solar cells can achieve high power conversion efficiency and can be successfully commercialized; however, the exploration of optimization strategies is still necessary. Here, we demonstrated improved performance of a polycrystalline silicon solar cell by depositing Sb2Ox/CdO double layers onto a Si wafer via a low-cost route. The metal oxide layers, forming effective heterojunctions, suppressed carrier recombination and reduced surface reflection. Additionally, the heterojunctions of Sb2Ox/CdO/Si enhanced the transmission of electrons and holes and simultaneously, a wider response range in the solar spectrum was realized. The power conversion efficiency improved from 12.6 to 16.7% in a polycrystalline silicon solar cell, with relative increase of 33%. It is expected that the metal oxide-enhanced devices will have tremendous potential in commercial applications.