The solution-processable transition metal oxide (TMO) interlayers have been developed as a scalable interlayer for inverted organic solar cells (i-OSCs). However, challenges remain for achieving a defect-free metal-oxygen network on the hydrophobic and thermally sensitive organic photoactive layer. Herein, we demonstrate the novel approach to eliminate chelating ligands in the MoOx precursors via an ionic-liquid (IL) catalyzed hydrolysis reaction for a simple room-temperature processable MoOx interlayer. The IL invokes an electron redistribution of sol-gel precursors, expediting the removal of the binding ligands. The densified Mo-O network resulted in a twenty-fold increase of electrical conductivity and superior work function tunability than the pristine one. The ionic-liquid-catalyzed MoOx thin film on top of the PBDB-TF:Y6:PC70BM photoactive layer enables the 17.6% efficiency. As a result, our method can contribute to the emerging large-scale and low-cost i-OSCs.