A glucose/air biofuel cell (BFC) that can convert both chemical and light energy into electricity is described. Polyterthiophene (pTTh), a photoresponsive conducting polymer, serves as cathode and catalyzes the reduction of oxygen. Taking advantage of the good environmental stability and exceptional optical properties of pTTh, the assembled BFC exhibits excellent stability and a fast photoresponse with an open-circuit voltage (Voc) of 0.50 V and a maximum power output density (Pmax) of 23.65 μW cm−2 upon illumination by visible light of 10 mW cm−2, which is an enhancement of ca. 22 times as compared to Pmax in the dark. Additionally, we propose a possible mechanism for this enhancement. Fabricating a BFC in this manner provides an energy conversion model that offers high efficiency at low cost, paving an avenue for practical solar energy conversion on a large scale.