Efficient solar-driven evaporation has engendered great interests as a sustainable and environmental approach for solar energy utilization. The development of high-performance photo-absorbers is of paramount importance for realizing efficient solar evaporation. Among the light-harvesting materials, transition metal oxide (TMO) is regarded as one of the most promising substitutes for photothermal conversion. Here, two-dimensional (2D) defective tungsten oxide (WOx) nanosheets are prepared via introducing oxygen vacancies in WO3. It demonstrates that the novel 2D plasmonic WOx nanosheets can be used as high performance photo-absorbers for efficient solar steam generation, displaying broadband and intense light absorption in the full solar spectrum due to the tunable localized surface plasmon resonances. Its evaporation efficiency reaches 78.6% under similar to 1 kW/m(2) (one sun) irradiation. The result reveals that adjusting the surface nanostructures and morphologies of TMO can be thought to be a potential strategy to promote the light-harvesting performance for solar steam generation. This study is significant for further exploring potential applications of plasmonic semiconductors in sterilization, desalination, and photothermal power through solar steam generation.