We report facile route to produce chitin fiber as a separator component in Li metal based oxygen battery by using rotary jet spinning (RJS) method. The chitin polymer extracted from squid pen, known as a β phase, is dissolved in Hexafluoroisopropanol (HFIP) solvent and bent out from a reservoir by a strong centrifugal force. Our simple but potent method allows fast production of chitin fiber consisting of hierarchically-aligned self-assembled chitin nanofibers. Following the scrutinization on the Chiber-Li ion interaction via DFT calculation, we demonstrate the potential of chitin fiber as a nonwoven mat-type separator by monitoring it in Li-O2 and Na-O2 cells.