AbstractHerein, we demonstrate that the intramolecular electron transfer within a single enzyme molecule is an important alternative pathway that can be harnessed to generate electricity. By decoupling the redox reactions within a single type of enzyme (for example, Trametes versicolor laccase), we harvested electricity efficiently from unconventional fuels including recalcitrant pollutants (for example, bisphenol A and hydroquinone) in a single‐laccase biofuel cell. The intramolecular electron‐harnessing concept was further demonstrated with other enzymes, including power generation during CO2 bioconversion to formate catalyzed by formate dehydrogenase from Candida boidinii. The novel single‐enzyme biofuel cell is shown to have potential for utilizing wastewater as a fuel as well as for generating energy while driving bioconversion of chemical feedstock from CO2.