The pure CdO and CdO/La 2 O 3 , and CdO/La 2 O 3 /PVP nanocomposites were synthesized by microwave irradiation method. The prepared samples are analyzed by X-Ray diffraction (XRD), Fourier Transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), Transmission electron microscope (TEM), UV visible spectrometer, Photoluminescence (PL), and Vibrating sample magnetometer (VSM). XRD and FTIR studies confirmed the formation of binary metallic nanocomposites. SEM and TEM analysis authenticate that the addition of lanthanum oxide and PVP influences the size and morphology of CdO nanoparticles the bandgap value can be tuned by the addition of La 2 O 3 and PVP. Photoluminescence spectra show the violet emission in the region between 432 nm to 460 nm and the green emission peak at 529 nm for all three synthesized samples. CIE color coordinates for CdO and CdO/La 2 O 3 , and CdO/La 2 O 3 /PVP nanocomposites were also estimated from emission spectrum. The VSM results confirmed that the nanocomposites possess the weak ferromagnetic properties due to the inclusion of La 2 O 3 and PVP. The dielectric constant, electrical conductivity and dielectric loss values at room temperature have been analyzed for CdO and CdO/La 2 O 3 , and CdO/La 2 O 3 /PVP nanocomposites. Among the three synthesized samples, the CdO/La 2 O 3 /PVP nanocomposite attain high electromagnetic shielding efficiency. Furthermore, the rare earth element lanthanum oxide and PVP enhances the efficiency of photocatalytic degradation of MB dye.