Herein, a nanocomposite consisting of graphene quantum dots, a deep eutectic solvent and carboxyl functionalized multiwall carbon nanotubes (GQDs + DES + MWCNTs-COOH) was prepared. After electropolymerization of L-arginine on the surface of a glassy carbon electrode modified with the GQDs + DES + MWCNTs-COOH nanocomposite, an electrochemical sensor was fabricated. The morphology of the GQDs + DES + MWCNTs-COOH/PARG surface was characterized via field emission electron microscopy. The sensor allowed excellent performance to be obtained for the analytical monitoring of paracetamol and its metabolite 4-aminophenol. Under the optimal conditions, the prepared electrochemical sensor exhibited wide linear dynamic ranges from 0.030 to 110 μmol L⁻¹ and 0.050 to 100 μmol L⁻¹ for paracetamol and 4-aminophenol, respectively. Moreover, the detection limits were 0.010 μmol L⁻¹ and 0.017 μmol L⁻¹, for paracetamol and 4-aminophenol, respectively. The practical applicability of the constructed sensor was explored by the determination of both compounds in human fluid samples and acceptable results were obtained.