In this study, the polyethylene oxide (PEO)/SiO2 nanoparticles (NPs) nanocomposite films with various SiO2 NPs concentrations were prepared using an in situ formation of NPs in the polymer matrix for self‐cleaning antireflected surface applications. The effect of SiO2 NPs in PEO/SiO2 NPs nanocomposite films on the structural, morphological, chemical, thermal, optical, and electrical properties of PEO/SiO2 NPs nanocomposite films was performed. According to the x‐ray diffraction and the differential scanning calorimetry analysis, the crystallinity degree of the nanocomposite films decreases by increasing the SiO2 NPs concentrations. The bandgap energy of PEO/SiO2 NPs nanocomposite films decreases from 3.95 to 3.55 eV as the SiO2 NPs concentration increases up to 10 wt.%. The average electrical conductivity of the PEO/SiO2 NPs nanocomposite films increases from 5.1 × 10−7 to 2.0 × 10−6 S/cm as the SiO2 NPs concentration increases up to 10 wt.%. The refractive index decreases to 1.64 at 550 nm for the PEO/SiO2 NPs nanocomposite films with 10 wt.% of SiO2 NPs, and the water contact angle decreases to around 0° after thermal treatment, which confirms that the PEO/SiO2 NPs nanocomposite films can be used as self‐cleaning antireflected surfaces. Morphological and particle dispersion of PEO/SiO2 nanocomposite films.