Organic–inorganic hybrid perovskite solar cells (PSCs) have been rapidly evolving as a promising candidate for next-generation photovoltaic technologies. P-type organics or polymers are generally used as hole transport materials (HTMs), which are expensive and non-sustainable for long-term applications. Herein, we demonstrate an inorganic Ni–Co–O hole conductor that displayed fast hole extraction and transport by the presence of gap states and relative high hole conductivity. Detailed structural inspection reveals that Co3+ and Ni2+ ions would reform into Co2+ and Ni3+ sites with the incorporation of Co, which contributes to greatly enhanced hole concentration. Inverted heterojunction devices based on NiCoOx hole transport layers yielded a maximum power conversion efficiency (PCE) of 20.03%, with 16.9% improvement compared with those based on NiOx layers (17.14%). This novel HTM with a facile synthesis process provides a new strategy for designing efficient carrier transport materials such that efficient charge collection and transport are achieved.