Cu-based nanocatalysts are the cornerstone of various industrial catalytic processes. Synergistically strengthening the catalytic stability and activity of Cu-based nanocatalysts is an ongoing challenge. Herein, the high-entropy principle is applied to modify the structure of Cu-based nanocatalysts, and a PVP templated method is invented for generally synthesizing six-eleven dissimilar elements as high-entropy two-dimensional (2D) materials. Taking 2D Cu2Zn1Al0.5Ce5Zr0.5Oxas an example, the high-entropy structure not only enhances the sintering resistance from 400 °C to 800 °C but also improves its CO2hydrogenation activity to a pure CO production rate of 417.2 mmol g−1h−1at 500 °C, 4 times higher than that of reported advanced catalysts. When 2D Cu2Zn1Al0.5Ce5Zr0.5Oxare applied to the photothermal CO2hydrogenation, it exhibits a record photochemical energy conversion efficiency of 36.2%, with a CO generation rate of 248.5 mmol g−1h−1and 571 L of CO yield under ambient sunlight irradiation. The high-entropy 2D materials provide a new route to simultaneously achieve catalytic stability and activity, greatly expanding the application boundaries of photothermal catalysis.