A cascade structured PbS/CuInS₂/TiO₂ photoelectrode with a co-sensitizer of CuInS₂ and PbS quantum dots (QDs) deposited on TiO₂ nanorods is fabricated via a successive ionic layer absorption and reaction (SILAR) method. The effects of SILAR cycle numbers of n and m for CuInS₂ QDs and PbS QDs, as well as the influence of the co-sensitization of QDs on the energy conversion efficiency, are discussed. The results show that the deposition of co-sensitizer PbS QDs on CuInS₂ QDs–TiO₂ nanorod array photoelectrodes presents a complementary effect in light absorption. The performance of quantum dot sensitized solar cells (QDSSCs) shows dominant dependence on the value of SILAR cycles n and m. The enhanced performance of QDSSCs with the cascade structure, PbS/CuInS₂/TiO₂ photoelectrode, is attributed to the Fermi energy level alignment of the QDs co-sensitizer. An energy conversion efficiency of 4.11% is achieved using the PbS/CuInS₂/TiO₂ photoelectrodes under one sun illumination (AM 1.5, 100 mW cm⁻²).