Calotropis gigantea fiber (CGF) is a typical cellulosic fiber with a unique hollow structure. When treated with NaClO₂ to improve its hydrophilicity, this fiber was further modified by polydopamine (PDA) from its rapid deposition using CuSO₄/H₂O₂ as a trigger, by which the nitrogen-rich CGF (NR-CGF) was achieved and subsequently, its adsorption properties to Ciprofloxacin (Cip) and Norfioxacin (Nor) were systematically investigated. The results indicated that NaClO₂-mediated oxidation process could greatly reduce the water contact angle of CGF from original 130° to 50°, while its unique hollow-structure was retained and then successfully modified by fiber-oriented PDA coating. Batch adsorption experiments demonstrated that NR-CGF had a highly efficient adsorption efficiency for fluoroquinolone antibiotics, with the adsorption capacity of 136.43 mg/g for Cip and 88.43 mg/g for Nor at initial pH of 8.0 and initial concentration of 100 mg/L. Meanwhile, >80% and >90% equilibrium adsorption can be achieved within 1 min and 10 min, respectively. After five adsorption-desorption cycles, no significant decrease in the adsorption capacity was observed. Given its fast adsorption kinetics, high adsorption capacity, excellent reusability and environmental friendliness, NR-CGF from green resource will find its promising application as a highly efficient adsorbent for removal of fluoroquinolone antibiotics from water.