•The facile & efficient I− removal was achieved by crosslinked chitosan microsphere.•The maximum adsorption capacity of I− was up to 0.8792 mmol/g in 40 min adsorption.•The crosslinked chitosan microspheres performed highly efficiently from pH4 to 10.•The CMs could be regenerated for five cycles and maintained the high efficiency. Radioactive iodine from the nuclear wastes was the significant environmental pollution, causing the health concern. Cross-linked chitosan microspheres (CM) by emulsion polymerization were investigated and proposed as the green and efficient adsorbents to treat iodine wastes via I− and -NH2 attraction. The I127 anions (instead of the radioactive iodine) adsorbed by CM were promising according to adsorbent dosage, pH, co-existing anions and recyclability analyzations through FTIR, SEM, BET and TGA. From pH 4 to 10, CMs maintained the I− adsorption efficiency no less than 95%. The maximum adsorption capacity of I− was up to 0.8792 mmol/g relative to the initial 2 mmol/L I− at pH 5 during 40 min adsorption, well-fitting with Freundlich isotherm model and pseudo-second order kinetic model. Moreover, the CMs after five regenerations maintained almost the same adsorption efficiency, and performed the differently competitive-adsorbed behavior. The CMs thus were prospective adsorbents for the iodide removal from waste water.