This study reports on the effect of UV-light on the mechanical properties of bio polymer thin films (BPF) doped with 10 % Titanium Dioxide (TiO2). Bio monomer was mixed with 4, 4-methylenebis (phenylisocyanate) (MDI) to produce neat BPF and TiO2 was added to form BPF doped with 10 % TiO2. The film samples were irradiated in UV Accelerated Weatherometer at 50 °C with different exposure time. Universal Testing Machine was used to measure the tensile strength and the fracture surfaces of the tensile specimens were observed by Scanning Electron Microscopy (SEM). The maximum tensile strength of UV irradiated neat BPF is lower than BPF doped with 10 % TiO2 of 3.5 MPa and 4.2 MPa respectively. Stress of neat BPF was decreased from 3.7 MPa to 3.2 MPa after 144 hours of UV exposure at 50 °C while BPF doped with 10 % TiO2 decrease from 4.7 to 3.6 MPa. The Modulus Young of neat BPF is lower than BPF doped with 10 % TiO2 which are 0.32 GPa and 0.33 GPa respectively. The cumulative strain percentage irradiated neat BPF is lower than BPF doped with 10 % TiO2 with 98.7 % and 113.7 % respectively. Unexposed UV light of neat BPF and BPF doped with 10 % TiO2 were observed by SEM shows smooth fracture and brittle fracture respectively. Neat BPF and BPF doped with 10 % TiO2 exposed to UV light show higher ductility property as compared to unexposed BPF. The higher the exposure time of BPF to UV light, revealed systematic increment of tensile strength due to increased crosslink between isocyanate and hydroxyl group.