Graphene (Gr) and other Gr-like two-dimensional (2D) materials, including hexagonal boron nitride and transition metal chalcogenides, have been widely investigated by researchers owing to their unique physical properties. Accordingly, the van der Waals heterojunctions formed by stacking these 2D layered materials have become a research hotspot because of their unique and excellent physical properties. Here, a large-area and high-quality single-layer Gr film and a molybdenum disulfide (MoS₂) monolayer were synthesized. The Gr film was patterned into microstrips using photolithography and plasma etching techniques. Finally, the MoS₂ monolayer was transferred onto the Gr strips to form the Gr-MoS₂ vertical heterojunction. Compared with that of the photodetectors based on the MoS₂ monolayer, the performance of the photodetectors based on the Gr-MoS₂ vertical heterojunctions significantly increase. The photocurrent and photoresponsivity of the photodetector based on the Gr-MoS₂ vertical heterojunction are 250 and 750 times those of the MoS₂ monolayer, respectively. The improved photoelectric performance proves that this heterojunction formed by stacking Gr and MoS₂ has broad application prospects in future optoelectronic devices and optoelectronic integrated circuits.