The strong aggregation tendency of hole transport material poly[3-(4-carboxylbutyl) thiophene-K (P3CT-K) restricts its further application in inverted perovskite solar cells (PSCs). Here, we report an effective strategy to address this issue and achieve the superior performance of inverted methylammonium lead triiodide (MAPbI₃) PSCs, in which graphdiyne oxide (GDYO) doped P3CT-K nanocomposites are applied as the hole transport nanolayer (HTL). It is revealed that the strong π–π stacking interaction occurs between GDYO and P3CT-K, which is proved by the blue shift of the absorption peak of P3CT-K nanolayer. The aggregation control via GDYO contributes to the property improvement of P3CT-K HTL. Moreover, the homogeneous coverage induces the growth of perovskite grain with larger size than that based on the undoped one. As a result, the optimized surface morphology, enhanced conductivity, charge extraction as well as better crystal quality, finally improve the device performance. An optimal power conversion efficiency of 19.06% is achieved, with simultaneously improved fill factor and short circuit current density. This work presents the potential of functional graphdiyne (GDY) in the development of highly efficient photovoltaic device.