Lignin is a renewable and abundant aromatic polymer found in plants. We herein propose a "cutting tail" methodology to produce phenol from lignin, which is achieved by combining Ru/CeO₂ catalyst and CuCl₂ oxidant via an oxidation–hydrogenation route. Phenol was obtained from separated poplar lignin with 13 wt % yield. Even raw biomass, such as poplar, birch, pine, peanut, bamboo willow, and straw, could be converted into phenol in 1–33 mg per gram of biomass.