A simple strategy to fabricate Cu single atoms (SAs) layer‐intercalated MoS₂ only by stirring Cu metals with MoS₂ nanosheets solution at room temperature is reported. An ultra‐high concentration (Cu: Mo = 98 at%) of Cu SAs is achieved and the intercalated Cu atoms strongly enhance the stability of the thermodynamically unstable 1T‐phase dominant MoS₂. Notably, the as‐synthesized MoS₂/Cu‐SAs exhibit a surprisingly high proportion of the metallic phase (64%) even after annealing at 800 °C in 5% H₂/Ar foaming gas, indicating extraordinary thermostability of the Cu intercalated 1 T‐MoS₂. In addition to, the as‐prepared MoS₂/SAs exhibit outstanding catalytic performance owing to the improved electrical conductivity and the highly active unsaturated Cu SAs. This strategy is confirmed as a universal method for producing SAs of other metals and other 2D nanosheets can also be used as the host for SAs intercalation other than MoS₂. This study may provide an effective strategy to fabricate facile and low‐cost SAs catalysts.