Necessity-oriented materials design has become a priority for every nation conscious of the well-being of the environment. A suitable environmentally friendly microwave-hydrothermal reaction was used to synthesize BaZrO3. A study of the properties of pure Si doped, and Bi–Si co-doped BaZrO3 semiconductors is presented. Crystalline structure, morphology and optical properties were dependent on the concentration of bismuth. Well faceted and spherical particles with increasing sizes from 90 up to 500 nm were obtained as the bismuth concentration increased. The highly crystalline compounds produced, maintain the BaZrO3 cubic perovskite phase even at bismuth–silicon concentrations as high as 50 and 1.5 mol%, respectively. The optical absorption edge shifts into the visible-light region and the band gap narrows as the bismuth concentration increases. Suitable compounds were obtained at reaction times of 1 and 4 h at 170 °C in water–ethanol solvent for non-doped BaZrO3 and doped BaZrO3, respectively. Since similar properties of other semiconductor materials have practical application as visible light-active photocatalysts, we propose the potential use of nanocomposite BaZrO3 as a green photocatalyst. The effects of bismuth–silicon inclusions on the properties of BaZrO3 and its relation with photocatalytic properties are exposed. HREM, HAADF and dopant distributions inside the perovskite structure are presented.