Here, we report a facile pyrolysis process to obtain an eco-friendly and sustainable oil-absorbing material by using a green plant fiber, i.e. Calotropis gigantea fiber with hollow tubular structure, as the starting raw material. The resulting carbon fiber keeps still the hollow structure in spite of shrinking size in diameter and curling edge in shape. When used as an absorbent, this carbon fiber can effectively and rapidly absorb a variety of model oils (including water-insoluble organic solvents), with the oil-absorbing capacity of up to 130 g/g within a few seconds. During the pyrolysis process, the pyrolysis temperature has a profound effect on the oil-absorbing capacity, while such a property is not greatly affected by the pyrolysis time. Further study implies that the carbon fiber can be well recovered by extracting with absolute ethanol to yield the full release of model oils (∼100%), and then reused for more than 10 cycles. Given its good hydrophobicity, high oil-absorbing capacity, good recyclability, and sustainable characteristics, such a hollow carbon fiber shows its potential applications as an efficient and sustainable oil-absorbing material for the removal and recovery of different oils in industry for environmental protection.