We have successfully synthesized pure and iron (Fe) doped tungsten trioxide (WO3) and nanothin films were deposited by chemical bath deposition method on glass substrates coated with FTO (F-doped tin oxide). The as-deposited films were annealed at 600 °C for 2 h in ambient atmosphere in order to improve crystallinity and structural perfection. The effect of Fe doping on structural, optical, and morphology of thin films was analyzed by X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectra, UV–Vis spectra, Photoluminescence (PL), and Atomic force micrograph (AFM) images. The XRD measurements showed that both the pristine and Fe doped WO3 films crystallize in monoclinic structure and the results are in good agreement with the standard JCPDS data (Card no: 83-0950). The surface of the films are very smooth and the calculated roughness value is around 28–17 nm, which is in good agreement with the average crystallite sizes calculated by Scherrer’s formula. The optical band gap energy of was found to be decreased from 3.12 to 2.92 eV with increase of Fe concentrations (0–10 wt%). The photocatalytic activities of the films were evaluated by degradation of methylene orange (MO and Phenol in an aqueous solution under visible light irradiation. The photocatalytic activity of Fe (10 wt%) doped WO3 film was much higher than that of the pure WO3. The improved photocatalytic mechanism by Fe doping is also discussed.