In this research work, nanocomposites of CuO/TiO2 were initially fabricated using drop casting method. Later on, these nanocomposites were irradiated for the first time by a beam of Argon ions (Ar[Formula: see text] by keeping the fluence rates of [Formula: see text] ions cm[Formula: see text], [Formula: see text] ions cm[Formula: see text], and [Formula: see text] ions cm[Formula: see text], respectively. In order to observe structural and optical properties of un-irradiated and irradiated nanocomposites, Raman Spectroscopy, Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Photoluminescence (PL) and Diffuse Reflectance Spectroscopy (DRS) analysis were performed. From Raman analysis, vibration modes confirmed the presence of different phases of TiO2 and CuO. EDX analysis clearly demonstrates the presence of Cu, Ti, and O peaks. SEM images depict agglomerated spherical nanoparticles having diameters in the range of 40–94[Formula: see text]nm. From TEM analysis, mean diameter of 56.1[Formula: see text]nm is observed for unirradiated and 33.7[Formula: see text]nm for Ar[Formula: see text] irradiated CuO/TiO2 nanoparticles in nanocomposite for fluence rates of [Formula: see text] ions cm[Formula: see text], [Formula: see text] ions cm[Formula: see text], and [Formula: see text] ions cm[Formula: see text]. HR-TEM and SAED images represent the polycrystalline nature of these nanocomposites. Among the three peaks of PL spectra in UV–Visible region, first two peaks were observed at 356[Formula: see text]nm, and 419[Formula: see text]nm but the third peak is little shifted from 488[Formula: see text]nm with the increase in fluence rate. Values of band gap are reduced from 3.29[Formula: see text]eV to 3.17[Formula: see text]eV as the fluence rate is increased, as calculated from results of diffuse reflectance spectroscopy.