tIn this study the effects of chemical modification of cellulose nanofibers (CNFs) on the biodegradabilityand mechanical properties of reinforced thermoplastic starch (TPS) nanocomposites was evaluated. TheCNFs were modified using acetic anhydride and the nanocomposites were fabricated by solution castingfrom corn starch with glycerol/water as the plasticizer and 10 wt% of either CNFs or acetylated CNFs(ACNFs). The morphology, water absorption (WA), water vapor permeability rate (WVP), tensile, dynamicmechanical analysis (DMA), and fungal degradation properties of the obtained nanocomposites wereinvestigated. The results demonstrated that the addition of CNFs and ACNFs significantly enhanced themechanical properties of the nanocomposites and reduced the WVP and WA of the TPS. The effects weremore pronounced for the CNFs than the ACNFs. The DMA showed that the storage modulus was improved,especially for the CNFs/TPS nanocomposite. Compared with the neat TPS, the addition of nanofibersimproved the degradation rate of the nanocomposite and particularly ACNFs reduced degradation rateof the nanocomposite toward fungal degradation.