Ultra-smooth thin films of bismite Bi2O3 synthesized by physical vapor deposition (PVD) have been inspected for their morphological, topographical, structural, and optical properties. Morphology and topography of the synthesized thin films were investigated by (SEM) and (AFM) and reveal a homogeneous nano-island structure with average grain size of 70 nm whereas the surface has a root mean square (RMS) roughness of 2.68 nm. The structural properties were investigated by (XRD) show the films having polycrystalline monoclinic structure of bismuth oxide. The optical properties were studied by spectrophotometer and reveal the films having narrow bandgap of 1.95 eV, the nonlinear optical constants were investigated by Wemple-DiDomenico model, the calculated values of the single-oscillator energy and the dispersion energy were found to be 4.01 eV and 23.26 eV; respectively, the third-order nonlinear susceptibility was found to be 7.72 × 10−12 esu. These characteristics show the films are good candidate for nonlinear optoelectronics and various potential applications.