The photocatalytic conversion of carbon dioxide into fuels and valuable chemicals is a promising avenue to address the challenge of environmental change. Plasma treatment as a popular and effective method to prepare and modify materials based on its ultra-high energy and efficiency has attracted significant attention. In this study, abundant Bi quantum dots (Bi QDs) are reduced in situ on the surface of black Bi₂WO₆ nanosheets using an effective dielectric barrier discharge (DBD) plasma technology. The reduction of Bi QDs leads to the generation of a large number of unsaturated coordination atoms, which improves the light absorption performance of Bi₂WO₆. Benefiting from the unique interface design, black Bi₂WO₆ shows superior CO generation rate, roughly threefold higher than that of pristine Bi₂WO₆ nanosheets. Our work provides new insights and can be a reference in plasma modification engineering of catalyst surfaces and photoreduction of CO₂.