Colloidal graphene/PbS quantum dots (QDs) hybrid nanostructures are fabricated with chemical grafting in one-pot solution methods. In the hybrid nanocomposites, PbS QDs are decorated on the reduced graphene oxide (rGO) nanosheets (NSs). By employing X-ray photoelectron spectroscopy (XPS) analysis, it is shown that the rGO NSs are bonded to PbS nanocrystals through oxygen functional groups, leading to improved surface passivation and electrical conductivity in the hybrids. The results obtained by the recordings of time-resolved photoluminescence spectra, field effect mobility, and photovoltaic performance revealed that rGO grafted to PbS QD composite structures provided better charge transport by 16 times compared to PbS alone, which is attributed to suppressed charge recombination and improved interfacial charge transport processes. Thus, the developed hybrid photoactive film enhanced open circuit current (J(sc)) and power conversion efficiency (PCE) by 12% and 14% correspondingly.