Herein, the fabrication of bioinspired moth‐eye antireflective (AR) films based on surface nanocomposites of poly vinylidene fluoride (PVDF) and TiO2 nanoparticles produced in a single thermal nanoimprint lithography step is described. The incorporation of nanoparticles enhances the mechanical and thermal stability of the AR topography as demonstrated by nanoindentation tests and in situ temperature‐dependent grazing incidence X‐ray scattering measurements using synchrotron radiation. The effect of thermal annealing and UV radiation on the degradation in the optical performance and durability of the AR films is also evaluated in weathering tests. Improving the thermal and mechanical behavior as well as the long‐term durability of nanoimprinted polymer AR films will significantly expand their potential for implementation in solar devices.