Abiotic 3D-printed cathodes for biofuel cells were manufactured using chitosan-cellulose nanofibres-iron doped graphene hydrogels and the cold material extrusion (MEX) 3D printing technique. The subsequent pyrolysis under ammoniac flux and in-situ n-doping of 3D cathodes led to the generation of conductive 3D electrodes with macroporosity that can be tuned by adjusting the linera infill in the 3D printing process and enhanced electrochemical activity. In-situ n-doped electrodes with 40% macroporosity provided a neat increase in specific current, i.e. from 13 µA/mg of 3D electrodes containing pre-doped graphene to 35 µA/mg of pyrolyzed ones, thus showing that MEX 3D printing followed by in-situ n-doping is a promising manufacturing process for the fabrication of high current density abiotic cathodes.