Organic/inorganic hybrid perovskite solar cells (PSCs) have represented a promising field of renewable energy in recent years due to the compelling advantages of high efficiency, facile fabrication process and low cost. The development of inorganic p-type metal oxide materials plays an important role in the performance and stability of PSCs for commercial purposes. Herein a facile and effective way to improve hole extraction and conductivity of NiOx films by manganese (Mn) doping is demonstrated in this study. A Mn-doped NiOx layer was prepared by the sol-gel process and served as the hole transport layer (HTL) in inverted PSCs. The results suggest that Mn-doped NiOx is helpful for the growth of perovskite layers with larger grains and higher crystallinity compared with the pristine NiOx. Furthermore, the perovskite films deposited on Mn-doped NiOx exhibit lower recombination and shorter carrier lifetime. The device based on 0.5 mol% Mn-doped NiOx as the HTL displayed the best power conversion efficiency (PCE) of 17.35% and a high fill factor (FF) of 81%, which were significantly higher than those of the one using the pristine NiOx HTL (PCE = 14.71%, FF = 73%). Moreover, the device retained 70% of its initial efficiency after 35 days' storage under a continuous halogen lamp matrix exposure with an illumination intensity of 1000 W m−2. Our results widen the development of PSCs for future production.