Cuprous oxide (Cu2O) is a nontoxic and earth-abundant semiconductor material, which is a promising candidate for low-cost photovoltaic applications. Although Cu2O-based solar cells have been studied for a few decades, they still suffer from disappointing photovoltaic performance due to its high trap-state density and inferior carrier collection efficiency. Herein, a facile solution method is demonstrated to synthesize high-quality Cu2O films with low defects as hole transport layers (HTLs) and the Cu2O/Si heterojunction solar cells are fabricated. Moreover, a variety of interfacial engineering and light management strategies are adopted to push the efficiency limit of Cu2O/Si solar cells, including a Ag transparent conductive layer, HNO3 passivation, Mg electrode back contact, and MoOx antireflection layer, which enable the boosting of carrier separation and reduce the loss of incident solar light, yielding a record high power conversion efficiency of 9.54%. This work may pave the way for economical and environment-friendly use of Cu2O/Si heterojunction solar cells in daily life.