Interface engineering that involves in the metal cathodes and the electron transport layers (ETLs) facilitates the simultaneous improvement of device performances and stability in perovskite solar cells (PSCs). Herein, low-temperature solution-processed cerium oxide (CeO_x) films are prepared by a facile sol-gel method and employed as the interface layers between [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM) and an Ag back contact to form PC₆₁BM/CeO_x double ETLs. The introduction of CeO_x enables electron extraction to the Ag electrode and protects the underlying perovskite layer and thus improves the device performance and stability of the p-i-n PSCs. The p-i-n PSCs with double PC₆₁BM/CeO_x ETLs demonstrate a maximum power conversion efficiency (PCE) of 17.35%, which is superior to those of the devices with either PC₆₁BM or CeO_x single ETLs. Moreover, PC₆₁BM/CeO_x devices exhibit excellent stability in light soaking, which is mainly due to the chemically stable CeO_x interlayer. The results indicate that CeO_x is a promising interface modification layer for stable high-efficiency PSCs.