Organic–inorganic halide perovskites possess excellent chemical, optical, and electronic properties that make them attractive for next-generation solar cells. In this paper, we introduce all-low-temperature processed perovskite solar cells using metal sulfide as an electron transport layer. First, we evaluated the alignment of energy levels at the perovskite/metal sulfide layer interface. The properties of metal sulfide and the perovskite layer, as well as the corresponding device performance, were then investigated. Using a CdS layer as an electron transport layer, we have achieved a maximum power conversion efficiency of 11.2% under reverse scans. The successful use of the CdS layer in perovskite solar cells likely would create new pathways and opportunities for the advancement of device design.