Hydroxypropyl methyl cellulose (HPMC)-based hybrid nanocomposites reinforced with bacterial cellulose nanocrystals (BCNC) were prepared and characterized. The HPMC nanocomposites exhibited good thermal stability, with a thermogravimetric peak temperature of around 346℃. The addition of BCNC did not significantly affect the thermal degradation temperature or improve the transparency of HPMC nanocomposites. However, the addition of BCNC favorably affected the light scattering properties of the nanocomposites and enhanced mechanical properties such as tensile stress and Young's modulus from 65 MPa and 1.5 GPa up to 139 MPa and 3.2 GPa, respectively. The oxygen permeability of the HPMC nanocomposites also increased with increase in the amount of BCNC added.