The selective adsorption materials are critical for solving the pollution problem caused by oil spills. In this study, a novel white radish-based cellulose aerogel is developed for efficient oil-water separation via a two-step hydrothermal treatment combined with subsequent freeze-drying and hydrophobic modification. The effects of different hydrothermal process on the adsorption capacity and recyclability of aerogels are studied. The results show that the aerogel prepared from white radish has high adsorption capacity (40–101 g/g) for various organic solvents and oil. Owing to the fact that the original parallel structure of cellulose fibers in white radish was inherited, the aerogel exhibits excellent elasticity and can be reused by squeezing-absorbing cycle. In addition, the high hydrophobicity (water contact angle of 142 °) endows the aerogel with a high separation efficiency of 96% to chloroform -water mixture. This environmentally friendly low-cost biomass aerogel is promising for efficient oil-water separation.