A novel myoglobin-gold nanoparticles-polydopamine-graphene (MGPG) polymeric bionanocomposite was applied for studying the immobilization and direct electrochemistry of redox protein. The MGPG bionanocomposite was synthesized by an efficient one-pot green polymerization approach. The direct electrochemistry studies of the MGPG bionanocomposite modified electrode demonstrated that the immobilized myoglobin (Mb) retained its bioactivity and exhibited strongly enhanced direct electrochemical redox activity. This is mainly attributed to the proper orientation of the immobilized Mb due to in-situ oxidative polymerization process, the large specific surface area of the nanocomposite, and the good conductivity of the graphene-Au nanoparticles complex. Hence, the present polymeric bionanocomposite displayed good electrocatalytic activity to the reduction of H2O2. The proposed method is highly recommended as a novel biosensing platform for biomolecules immobilization, which can further expand the applications of biosensing and biocatalysis, such as construction of third generation biosensors and the detection of H2O2 released by cells. (C) 2016 Elsevier B.V. All rights reserved.