Growing e-waste and the dwindling of non-renewable materials underscores the urgency to develop electronics based on renewable natural resources. Using cellu-lose as a material for 3D printing living fungal electrodes, is a novel way to harness their metabolic activity for potential use in electrochemical devices. This study shows that the yeast Saccharomyces cerevisiae and the white-rot fungus Trametes pubescens in combination with cellulose nanocrystals (CNC) and cellulose nano-fibrils can be 3D printed and that both fungi grow inside the inks. Adding carbon black and graphite flakes to the inks makes them electronically conductive for po-tential use as electrodes in fungal batteries, specifically microbial fuel cells (MFC). A single battery produces a maximum power density of 12.5 μW/cm2 and a maxi-mum current density of 49.2 μA/cm2 (22 kΩ). These fungal biobatteries can produce between 300-600 mV for several days, delivering 3-20 μA for external loads be-tween 10 and 100 kΩ. Attaching four batteries in parallel can power a small sensor for 65 hours. Also, a fully biodegradable fungal MFC can be constructed with bees-wax and a customized cellulose proton exchange membrane. This is the first study that reports on 3D printed cellulose-based fungal electrodes in an MFC.