Prawn waste, a chitinous solid waste of the shellfish processing industry, was used as a substrate for chitinase production by the marine fungus Beauveria bassiana BTMF S10, in a solid state fermentation (SSF) culture. The process parameters influencing SSF were optimized. A maximum chitinase yield of 248.0 units/g initial dry substrate (U/gIDS) was obtained in a medium containing a 5:1 ratio (w/v) of prawn waste/sea water, 1% (w/w) NaCl, 2.5% (w/w) KH2PO4, 425–600 μm substrate particle size at 27 °C, initial pH 9.5, and after 5 days of incubation. The presence of yeast extract reduced chitinase yield. The results indicate scope for the utilization of shellfish processing (prawn) waste for the industrial production of chitinase by using solid state fermentation.