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 N-2 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 N-2 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.