Efficient charge extraction at the interface between the perovskite and the hole transport layer (HTL) is crucial for high-performance inverted perovskite solar cells (PSCs). However, the conventional poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) suffers from intrinsic hydrophobic surface limit the overall performance of PSCs. In this study, we synthesized a carboxylic acid-functionalized PTAA (CA-PTAA) to improve the interfacial properties. The introduction of carboxylic acid groups enhances the surface wettability of the HTL, promoting the growth of a high-quality perovskite film with minimized interfacial defects. Furthermore, two-side photoluminescence (PL) measurements suggest suppressed defect losses and efficient charge transfer. Consequently, the CA-PTAA-based PSCs achieved a power conversion efficiency (PCE) of 22.77%, compared to the 19.98% of the control device. The molecular engineering of polymeric HTLs is an effective strategy for high-performance inverted PSCs.