ABSTRACT: Photodegradable poly(lactic acid) (PLA)/titanium dioxide (TiO2) nanocomposites could be utilized as an eco‐friendly material. The photocatalytic degradation was investigated under accelerating artificial ultraviolet irradiation conditions for the period up to 100 days according to GB/T16422.3/ISO 4892.4. The change of surface color, gloss loss, morphology, weight loss, intrinsic viscosity, chemical structure, mechanical properties at different irradiation times were verified via solid reflection spectrophotometer, scanning electron microscopy, Ubbelohde viscometer, Fourier transform infrared spectrometer, and tensile test. The structural change accompanied by the degradation of the irradiated samples clearly showed that the photodegradation of PLA/TiO2 nanocomposites process was via a bulk erosion mechanism. The photodegradability of PLA/TiO2 samples was higher than that of pure PLA and benefitted a lot from a good dispersion of TiO2 nanoparticles. The present study suggests that the photodegradation of PLA could be controlled by loading dispersed g‐TiO2 nanoparticles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46509. [ABSTRACT FROM AUTHOR]