Jackfruit filum polysaccharide (JFPS) was extracted and confirmed to contain neutral and acidic polysaccharides, largely composed of acidic polysaccharides. Biodegradable JFPS–titanium dioxide (TiO₂) nanocomposite films were fabricated using the solvent casting method combined with photocatalysis. The result of scanning electron microscopy (SEM) shows a uniform distribution of TiO₂ nanoparticles into the gelatin matrix. Incorporation of TiO₂ into the JFPS matrix significantly decreased the transparency, moisture content and total soluble matter. Surface hydrophobicity also decreased, the mechanical properties and thermal stability of the JFPS films improved. The JFPS/TiO₂ nanocomposite films exhibited strong antibacterial activity against Escherichia coli and Staphylococcus aureus. The films incorporated with 3% (w/w) TiO₂ showed the best mechanical properties and thermal stability, as well as excellent antimicrobial activity against Escherichia coli (78.9%) and Staphylococcus aureus (60.57%). The data of Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD) indicate that photocatalysis might contribute to the formation of the strong interfacial interaction between the JFPS matrix and TiO₂ nanoparticles. Finally, these results demonstrated the feasibility of introducing photocatalysis to prepare nanocomposite films, and it is of significance in utilizing the JFPS and TiO₂ to produce biodegradable nanocomposite films as packaging material in food and non-food industries.