Humins are a by-product of the hydrolysis of carbohydrates in the production of levulinic acid. With the development of new large-scale processes to produce levulinic acid, the production of large amounts of this by-product will demand new applications beyond burning in biomass furnaces. Owing to its carbonaceous nature, many value-added applications have been considered. One of these applications is in the production of carbon-based electrodes for batteries. Such application has great potential because of the increasing need for the development of new cost-competitive energy storage technologies with enhanced specific energy. In this context, Li-O2 batteries are a technology with potential specific energy higher than current state-of-the-art lithium-ion batteries. This work reports the synthesis of a humins-based O2 electrode for a Li-O2 battery. Humins synthesized as a by-product of hydrolysis of sugars were purified via leaching, dried, and thermally treated under an inert atmosphere to enhance their electronic conductivity. The obtained product was then mixed with a binder and templated over a stainless-steel mesh to obtain the O2 electrode. Batteries were assembled with electrodes based on humins from both sugarcane bagasse and molasses. Humins were analyzed via X-ray photoelectron spectroscopy and scanning electron microscopy before and after treatments, and the electrodes were analyzed before and after the discharge of the battery. Results of deep discharge demonstrate the potential for this material for the manufacturing of carbon-based electrodes for batteries.