Pure In₂O₃ and mixed Mn₂O₃–In₂O₃ nanomaterials were synthesized via vapor transport method. The X-ray diffraction patterns demonstrated the cubic crystalline phase for pure In₂O₃ sample, whereas a combination of cubic In₂O₃ and orthorhombic Mn₂O₃ phases were observed for the mixed sample. The scanning electron microscopy images revealed the formation of randomly oriented nanorods for pure In₂O₃ sample, while assemblies of nanorods with different lengths and diameters were reported for the mixed sample. The transmittance spectrum of pure In₂O₃ was greater than 80% over the visible spectral range, while the transmittance of the mixed Mn₂O₃–In₂O₃ nanostructured film was 32%. The obtained band gap values for pure In₂O₃ and mixed Mn₂O₃–In₂O₃ nanostructured thin films were 3.92 and 3.37 eV, respectively. The mixed Mn₂O₃–In₂O₃ nanostructured thin film has higher refractive index, higher optical conductivity, and lower electrical resistivity than those for pure In₂O₃ film. Two obvious emission peaks were observed for the pure and the mixed samples. The photoluminescence intensity of the mixed Mn₂O₃–In₂O₃ nanostructured thin film is higher than that of pure In₂O₃ indicating its validity to be used in optoelectronic applications such as light-emitting diodes.