Undoped and reduced graphene oxide (r-GO)-doped CdO films were prepared via the ultrasonic spray pyrolysis method with weight ratios of 1, 3 and 5% onto substrates. The successfully prepared films were characterized to understand the influence of r-GO dopant content on the morphological, structural, electrical and optical properties of the films by several diagnostic techniques. XRD measurement confirms that all the films were polycrystalline in the cubic phase of CdO with the preferred orientation (111). The optical band gap of the films decreases with the increase in doping amount. The r-GO@CdO nanostructured films were used as an interfacial layer to fabricate the heterojunction device and to investigate their electrical properties using current-voltage and capacitance-voltage measurements in the dark. The rectification properties of the studied devices increase with the r-GO dopant amount. The obtained results indicate that the r-GO content in the CdO films is responsible for the modification of physical properties of electronic device.