Nonstoichiometric tungsten oxides (WO3-x) with abundant oxygen vacancies were synthesized and used as nonmetallic plasmonic photocatalysts to promote ethanol dehydrogenation under UV-visible light irradiation. Plasmonic WO3-x have unique electronic structures that act as Z-scheme heterostructures. UV-excited photoelectrons were injected into the conduction band of WO3-x, stabilizing the free electron density and boosting plasmonic hot electron generation for ethanol dehydrogenation. The synergetic effect of UV and visible light excitations greatly enhances the aldehyde generation to 2696 μmol g-1 (3 hours) with a high selectivity of 91%, which is 74-fold and 12-fold higher than those obtained under only UV or visible light irradiation, respectively.