We also found that a selective heparin capture can be realized via adjusting salt concentration or pH. Finally, we showed that after several recycle rounds, the heparin-recovery ability of the cationic nanocrystals was largely retained and the majority of active heparin dose was recovered, showing a significantly higher heparin-recovery performance than the commercial Amberlite IRA-900 and demonstrating its applicability from an economic perspective. Therefore, the reported cellulose nanocrystal-polymer conjugate represents a promising candidate for a green and efficient heparin recovery.