Inorganic perovskite CsPbBr₃ quantum dots (QDs) are potential nanoscale photosensitizers; moreover, two-dimensional (2-D) molybdenum disulfide (MoS₂) has been intensively studied for application in the active layers of optoelectronic devices. In this study, heterostructures of 2D-monolayered MoS₂ with zero-dimensional functionalized CsPbBr₃ QDs were prepared, and their nanoscale optical characteristics were investigated. The effect of n-type doping on the MoS₂ monolayer after hybridization with perovskite CsPbBr₃ QDs was observed using laser confocal microscope photoluminescence (PL) and Raman spectra. Field-effect transistors (FETs) using MoS₂ and the MoS₂–CsPbBr₃ QDs hybrid were also fabricated, and their electrical and photoresponsive characteristics were investigated in terms of the charge transfer effect. For the MoS₂–CsPbBr₃ QDs-based FETs, the field effect mobility and photoresponsivity upon light irradiation were enhanced by ~ 4 times and a dramatic ~ 17 times, respectively, compared to the FET prepared without the perovskite QDs and without light irradiation. It is noteworthy that the photoresponsivity of the MoS₂–CsPbBr₃ QDs-based FETs significantly increased with increasing light power, which is completely contrary to the behavior observed in previous studies of MoS₂-based FETs. The increased mobility and significant enhancement of the photoresponsivity can be attributed to the n-type doping effect and efficient energy transfer from CsPbBr₃ QDs to MoS₂. The results indicate that the optoelectronic characteristics of MoS₂-based FETs can be significantly improved through hybridization with photosensitive perovskite CsPbBr₃ QDs.