The electron transport layer (ETL) of fiber perovskite solar cells (fPSCs) is involved in transporting electrons and blocking holes. In this work, we added a SnO2 film on the TiO2 surface to form a double-layered TiO2/SnO2 ETL to improve electron mobility and device performance. The resulting double ETL results in more uniform surface morphology and the pores in the perovskite film are greatly reduced, which increases the size of perovskite crystal particles. The resulting power conversion efficiency (PCE) increased from 2.46% to 3.81% on adding the SnO2 layer to TiO2, resulting in a 54.8% improvement. Thus, this double-layered ETL structure facilitates the development of smart textiles woven from fPSCs for portable electronics.