Nanostructured CdS thin films are fabricated by a simple spin‐coating method at various annealing temperatures from 200 to 350 °C. CdS films of 80 nm thick, which are composed of nanoparticles or flakes with size ≈20–200 nm, are obtained. The nanostructured morphology is identified by scanning electron microscopy measurement. Sb2S3 films with large‐sized grains are deposited on the CdS thin films with hydrothermal method, in which CdS is adopted as electron transport layer (ETL) for Sb2S3 solar cells. The power conversion efficiency (PCE) is 4.88% for the best solar cell based on nanostructured CdS ETLs. Herein, a very facile and effective route to fabricate nanostructured CdS buffer layer for Sb2S3 solar cells is offered.