Herein, a new method for synthesizing advanced nanocomposite materials based on tungsten, molybdenum, and titanium oxides by pulsed underwater plasma is reported. This is an environmentally friendly, energy‐saving, and simple method for obtaining bimetallic oxide nanoparticles with inhomogeneous defect structures. The chemical composition and morphology of the obtained particles are explored by electron microscopy and X‐ray diffraction spectroscopy. Four types of mixed‐oxide particles of tungsten–molybdenum and tungsten–titanium are synthesized and used to make the photoanodes for dye‐sensitized solar cells (DSSCs). The best DSSC shows a fill factor of 51% and a short‐circuit current density of 4.8 mA cm−2, resulting in a conversion efficiency of 4.11% and an improvement over the cells prepared from pure titanium or tungsten oxides.