In the low Earth orbit (LEO) space, transparent polyimide (PI) films with high transmittance and strong resistance to atomic oxygen (AO) are pursued for providing effective protection and energy harvesting for novel lightweight solar arrays in spacecraft. In this work, hollow silica nanospheres (HSNs) were inlaid in transparent PI films for the formation of an HSN/PI composite structure, where the HSNs were first generated by a solution-based removal of organic templates from PAA-silica core-shell nanospheres, free from common high-temperature treatments, and then transferred to PI substrates. The HSN/PI composite structures resulted in the higher transmittance and stronger resistance to AO than did the pristine PI: the composite flexible films showed an average transmittance of 92.43% at broad wavelengths (400-1600 nm) and an AO erosion yield of 4.67 x 10(-26) cm(3)/atom after an AO exposure of 6.05 x 10(20) atoms/cm(2), which were superior to those of the pristine PI (90.80% and 1.33 x 10(-24) cm(3)/atom, respectively). Simultaneous realization of antireflective (AR), AO resistant, and mechanically robust PI composite flexible films provides new solutions to traditional AR patterned AO-resistant PIs and insights into the multifunctionalization of PIs in the LEO space environment.