The present work aims to develop electroanalytical strategies for separating and quantifying one of the most important biothiols, the reduced glutathione (GSH), based on developing and applying a new and selective magnetic molecular imprinted polymer (mag-MIP). This magnetic-supported polymer was synthesized by precipitation, using GSH as a template, having acrylamide as the functional monomer and trimethylolpropane trimethacrylate as a cross-linking agent. These materials' morphological and physical characteristics were investigated by scanning electron microscope, Fourier transform infrared, and vibrating sample magnetometry. Physicochemical parameters, such as adsorption capacity, were obtained and compared with the respective mag-NIP, which are control polymers without the selective cavity. After all characterizations, mag-MIP and mag-NIP were evaluated on magnetic graphite-epoxy composite (m-GEC) electrodes. The characteristics of the obtained sensors were investigated by cyclic voltammetry and differential pulse voltammetry. After optimizing experimental and operational conditions, a linear response for the concentration of GSH, in the range of 1–1400 μmol/L, with low detection and quantification limits of 7 and 20 nmol/L, respectively, were obtained. The GSH levels in mice liver samples were measured by electrochemical and spectrophotometric techniques to compare the method's effectiveness. A high correlation between them and a low relative error of 1.06 % were obtained, indicating the good functionality of the proposed sensor.