2D MoS₂ is one of the most intensely studied 2D materials. The material holds mechanical properties of 2D materials and unique bandgap, catalysis performance, consequently the material has attracted wide attention from research community toward polymeric materials. Firstly, the structures and performance of 2D MoS₂ were simply introduced. Then the preparation methods of 2D MoS₂/polymer nanocomposites were reviewed. It is found that melt mixing, solution blending and in-situ polymerization all could be used to produce the nanocomposites, however, in-situ polymerization could realize better dispersity for 2D MoS₂ in polymeric matrix. Thirdly, improvement of 2D MoS₂ toward performance of polymers was presented. It is found that 2D MoS₂ could enhance mechanical, heat resistance, flame retardancy, electrical conductivity and dielectric properties, proving that 2D MoS₂ is an excellent comprehensive additive for polymeric materials. Fourthly, the application of 2D MoS₂/polymer nanocomposites in sensing, detection, separation, environmental protection, energy and medicine health were reported. Finally, the future challenges on 2D MoS₂/polymer nanocomposites were summarized.