TiO2 is the most widely used photocatalytic material, but its wide application is restricted by low photocatalytic efficiency and tedious operation to recover the powder catalyst. To overcome these drawbacks, we synthesized highly photoactive nanocrystalline Co–B codoped TiO2/SiO2 composite films with narrowed band gap (2.29 eV) through an improved sol-gel process. The FE-SEM results showed that the Co–B codoped TiO2/SiO2 film without cracks was composed of smaller nanoparticles or aggregates compared to pure TiO2 film. The BET surface area results revealed that the specific surface area of Co–B codoped TiO2/SiO2 sample was 163.8 m2 g−1, while that of pure TiO2 was 47.9 m2 g−1. The DRS and PL spectra results indicated that the Co–B codoping and SiO2 compositing could not only induce strong visible light absorption but also reduce the recombination rate of electron–hole pairs. The photocatalytic properties of the films were evaluated by degradation of methyl green and oxytetracycline. Experimental results exhibited that the Co–B codoped TiO2/SiO2 film had the excellent photocatalytic activity under visible light irradiation.