3D printing has recently triggered huge attention in several fields such as construction, artificial tissue engineering, food fabrication, wearable electronics, and electrochemical energy storage. This work investigates the fabrication of a 3D-printed abiotic cathode for implantable glucose/oxygen biofuel cells. The ink formulation was optimized to get printable ink with high electro-catalytic activity. Electrode macro porosity was screened in order to identify the better compromise between electrode density and electrochemical performance. A maximum current density of 260 μA/cm2 was obtained with cylindrical electrodes with linear mesh infill and a volumic infill rate of 40%. A complete biofuel cell was assembled using a 3D-printed abiotic cathode and an enzymatic anode in the form of a compressed pellet showing maximum power and current densities of 80 μW/cm2 and 320 μA/cm2, respectively. Moreover, the hybrid biofuel cell was implanted in the intraabdominal region of a rat for three months and after cell explantation, the abiotic cathode displayed a 50% decrease in the current density while the enzymatic anode did not display any residual activity. The 3D printed electrode displayed a 2–3.6 fold increase in current density when compared to homolog 2D electrodes. Implantation of the biofuel cell in a free-living rat for 1–3 months. Display omitted •Nanocellulose-chitosan and N-doped graphene are used for cathode formulation.•3D printed cathodes provide a 3.6-fold increase in current density.•Fuel cell implantation in a rat does not induce severe inflammatory reactions.