The optical properties of various nanomaterials make them quite interesting and play a vital role in the fabrication of devices used in the optoelectronic and photonic fields. The research community around the world is curios to understand the physical phenomena behind such nanomaterials. In this study, copper oxide (CuO) nanoparticles (NPs) were prepared by a sonochemical method and their detailed optical properties analyzed by ultraviolet–visible (UV–Vis) spectroscopy. The normal dispersion of the refractive index of the CuO NPs was illustrated by the Wemple–DiDomenico single-oscillator method to yield the oscillator strength, static refractive index, dispersion energy (Ed), energy of effective dispersion oscillator (Eo), carrier concentration, and N/m* values. In addition, nonlinear optical parameters such as the refractive index, third-order nonlinear susceptibility, and optical polarization were also estimated. The nonlinear optical performance of the CuO NPs was simulated by using optiFDTD software, and the acceptance angle, spectral bandwidth, and nonlinear output power obtained. The findings could be used in optoelectronic device applications.