Despite of superior performance of the oxide-derived copper (OD-Cu) in producing valuable hydrocarbons during CO₂RR, its fabrication process is still ambiguous and complicated. In this work, we develop a simple microwave-assisted method to synthesize the oxide-derived Cu nanosheet (OD-Cu NS) and reveal that the oxidation state of Cu species is controlled by varying the Cu precursor amount. Notably, the simultaneous formation of nano-sized Cu domains influence the surface roughness of OD-Cu NS. The partially oxidized Cu surface exhibits a superior faradaic efficiency (FE) of C₂₊ products up to 72%, along with a partial current density of 55 mA cm⁻² in a neutral KHCO₃ solution. More importantly, the as-obtained OD-Cu NS shows a synergetic effect on dissociating of CO₂ molecules by the strong binding energy and promoting of C₂₊ compounds productivity by the enlarged electrochemical surface area. This work provides a new insight for designing efficient OD-Cu catalysts towards CO₂RR.