Molybdenum disulfide (MoS) and a layered organic-inorganic Ruddlesden-Popper perovskite (RPP) show promising optoelectronics applications due to the splendid photoresponse. On consideration that each material has a specific favorable window for light excitation, it is naturally of interest to integrate both for broadening absorption and synergistic interlayer coupling. Herein, on the basis of density functional theory (DFT) computations, we investigate a two-dimensional (2D) MoS/BAPbIRPP van der Waals (vdW) heterostructure by stacking monolayer MoSand 2D BAPbIvertically. We find that the MoS/BAPbIvdW heterostructure maintains a robust direct band gap with an enhanced light absorption that has a high solar to energy conversion efficiency. Moreover, the conduction band minimum (CBM) and the valence band maximum (VBM) are staggered and separately distributed within MoSand BAPbI, respectively. Interestingly, the MoS/BAPbIheterostructure shows a typical type II and S scheme interface arising from appropriate alignments of the Fermi levels and band edges between MoSand BAPbI. Such a heterostructure enables the efficient separation of photoexcited electrons toward the MoSside and holes via the BAPbIlayer and thus a strong redox ability that is ideal for photocatalyst and solar cell applications.