Hybrid photocatalysts were constructed by mixing W18O49 with commercial TiO2 (P-25) and tested for photodegradation of pollutants (methyl orange and phenol). W18O49 synthesized by alcohothermal method possesses urchin-like structure, high surface area of 178 m2 g−1 and wide light absorption in 200–800 nm. Although W18O49 alone shows low photoactivity, the hybrid shows significant synergetic promotion. The activity of W18O49(10 wt%)/TiO2 under UV–vis light and W18O49(90 wt%)/TiO2 under visible light is 2.43 (2.64) and 1.31 (1.52) times of calculated value without considering the synergy for the degradation of MO (phenol), respectively. Controlled experiments indicate ·O2− from reduction of O2 by photo-induced electrons is the key active species in the photodegradation. The synergy was attributed to the well-matched band structure of two semiconductors that enhances charge separation, with electrons moving to W18O49 and holes to TiO2, as confirmed by photo-deposition of Au and PbO2. Furthermore, W18O49/TiO2 is much more active than WO3/TiO2 attributed to the good reductive capability and wide light absorption of oxygen vacancies in W18O49. Moreover, the unstable W18O49 shows excellent stability in the hybrid.