In this paper, we fabricated poly(3,4-ethylenedioxythiophene) (PEDOT)–graphene oxide–polyphenol oxidase (PEDOT–GO–PPO) as a dopamine sensor. The morphology of PEDOT–GO–PPO was observed using scanning electron microscopy. Cyclic voltammetry was conducted to study the oxidation–reduction characteristics of dopamine. To optimize the pH, potential and limit of detection of dopamine, the amperometric technique was employed. The found limit of detection was 8 109 M, and the linear range was from 5 108 to 8.5 105 M. The Michaelis–Menten constant (Km) was calculated to be 70.34 mM, and the activation energy of the prepared electrode was 32.75 kJ mol1. The electrode shows no significant change in the interference study. The modified electrode retains up to 80% of its original activity after 2 months. In the future, the biosensor can be used for the quantification of dopamine in human urine samples. The present modified electrode constitutes a tool for the electrochemical analysis of dopamine.