The goal of this project is to obtain poly(vinyl alcohol) (PVA)/TiO2‐bovine serum albumin (BSA) nanocomposite (NC) films in different weight percentages of modified TiO2. For this purpose, to prevent the accumulation of nanoparticles (NPs) in the PVA matrix, the surface of the TiO2 NPs was treated with the BSA molecules. To achieve this aim, ultrasonic waves were used as an environmentally friendly and green process that decrease the time of reactions, help better spreading of TiO2 NPs and maintain dimensions of TiO2 NPs in the nanoscale range. In the end, the features of the PVA/TiO2‐BSA NC films were considered with a variety of techniques. The Fourier transform infrared spectroscopy, energy dispersive X‐ray, and X‐ray diffraction showed that the BSA was well placed on the surface of TiO2 NPs. The thermal gravimetric analysis and UV‐visible results demonstrated that all the PVA/TiO2‐BSA NC films have better thermal and optical properties than the pure PVA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46558.