SiO₂/BiOX (X = Cl, Br, I) thin films, which were well adhered to glass substrates with SiO₂ as the intermediate layer, were prepared via a simple sol–gel method. The prepared films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and Raman. The results suggest that the films have a tetragonal PbFCl-type structure and crystallized well. These films showed high and stable photocatalytic activities for the degradation of RhB under visible light. This method is cheap and convenient, the size and morphology of the product are uniform, the production cycle is short, and the process is applicable to large-scale applications. SiO₂/BiOX (X = Cl, Br, I) films might have promising applications in photocatalysis, photovoltaic film devices, nano-coating, pearlescent pigments and other fields.