Because of increasing numbers of oil spill accidents, considerable attention has been paid to the development of effective and inexpensive oil sorbents. Carbonized cotton fibers (CCFs) with a hollow tubular structure were successfully prepared by treating natural cotton in a N2 atmosphere and used as high-capacity oil sorbents. The material properties of the as-prepared CCFs were investigated by scanning electron microscopy, X-ray diffraction, contact-angle measurements, and N2 adsorption- desorption. Maximum oil sorption tests indicated that CCFs-400 showed the highest oil adsorption capacity and could absorb up to 32-77 times its own weight in pure oils and organic solvents, suggesting an increase of 27-126% compared with the capacity of cotton fibers. Also, repeatability, selectivity, and floating-ability tests suggested that CCFs-400 showed much better performance than cotton fibers in pure oil medium or water-oil mixtures. Owing to their multiscale porous structures, superhydrophobicity, and superoleophilicity, the CCFs demonstrated great potential as low-cost and effective sorbents in oil adsorption.