AbstractMultinary layered 2D nanomaterials can exhibit distinct physicochemical properties and innovative applications as compared to binary 2D nanomaterials due to their unique crystal structures. However, it still remains a challenge for the high‐yield preparation of high‐quality multinary 2D nanosheets. Here, the high‐yield and large‐scale production of two quaternary metal thiophosphate nanosheets are reported, i.e., Ni₃Cr₂P₂S₉ and Ni₃Cr₂P₂Se₉, via the liquid exfoliation of their layered bulk crystals. The exfoliated single‐crystalline Ni₃Cr₂P₂S₉ nanosheets, with a lateral size ranging from a few hundred nanometers to a few micrometers and thickness of 1.4 ± 0.2 nm, can be easily used to prepare flexible thin films via a simple vacuum filtration process. As a proof‐of‐concept application, the fabricated thin film is used as a supercapacitor electrode with good specific capacitance. These high‐yield, large‐scale, solution‐processable quaternary metal thiophosphate nanosheets could also be promising in other applications like biosensors, cancer therapies, and flexible electronics.