Herein, we introduce a novel modification process for carbon paste electrode by magnetic core–shell nanocomposite of graphene oxide/Fe3O4@SiO2 and n-hexyl-3-methylimidazolium hexafluoro phosphate as ionic liquid. Electrochemical features of this modified carbon paste electrode and its performance evaluation in simultaneous detection of acetaminophen and tyrosine via voltammetric oxidation was investigated. Moreover, diagnostic techniques including cyclic voltammetry, square wave voltammetry and chronoamperometry were applied in order to study the electrochemical oxidation behavior of this sensor toward acetaminophen. According to square wave voltammetry results, linear dynamic range between 1.0 × 10–6–1.0 × 10–3 M was observed for acetaminophen. The function of modified electrode in real samples containing acetaminophen and tyrosine was satisfactory.