Rigid substrate e.g. glassy carbon is typically used in biofuel cells (BFCs). Compared with the substrates, paper-based materials are low cost, lightweight, flexible design and easy to manufacture. In this work, flexible BFCs have been constructed on filter papers coated with a composite material of cellulose and carbon nanotube as binder. For mediator-less electrode reactions, biliribin oxidase and fructose dehydrogenese were employed as cathodic and anodic biocatalysts respectively. The power of a BFC unit reached 4.3μW while the cathode was the main limitation based on discharge experiments. The BFCs can be designed and constructed to various shapes on paper substrates in series and parallel configuration, a maximum power output of 7.9μW was produced. The voltage reversal behavior of individual cell in stack has also been investigated for the first time, which was caused by the unit with lowest ability in power generation in stack. This unique BFC obtained here is promising to be used as a kind of flexible power resources for wearable or rolling-up devices in practice.