The proof-of-concept for enzymatic electrosynthesis with simultaneous energy production has been demonstrated by using the regioselective conversion of D-sorbitol to D-fructose by D-sorbitol dehydrogenase as a model reaction. The bioreactor was composed of two electrodes, a carbon felt bioanode modified by multi-walled carbon nanotubes (MWCNT) containing D-sorbitol dehydrogenase immobilized in a silica matrix and an oxygen gas-flow cathode. The electrochemical regeneration of the NAD+ cofactor at the bioanode was achieved by using a poly(methylene green) mediator electrodeposited on the carbon felt/MWCNT electrode. The conversion rate was 1.18mgday−1cm−3 and an energy power output up to 14.6μWcm−3at 0.1V was reached.