In recent years, the continuous and uncontrollable presence of drug contaminants and their destructive effects on the environment has been raised as an environmental problem. A large proportion of drug contaminants are related to sedatives. Paracetamol is one of the most widely used sedatives in the world. In this study, the photocatalytic degradation of paracetamol under visible light in the presence of poly(glycidylmethacrylate)@polyaniline/CuO nanocomposite as a photocatalyst was investigated. This prepared nanocomposite was characterized by different techniques such as Fourier transform infrared (FT‐IR), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and transmission electron microscopy (TEM). The effect of various parameters such as the amount of photocatalyst, irradiation time, temperature, and pH of the solution was studied on drug degradation. The degradation of paracetamol (PA) was assessed by adding a number of radical scavengers to the solution. More than 99% of paracetamol (10 mg L−1) was degraded under operating conditions in 90 min.