Thermoplastic starch (TPS) is considered as alternative material for substitute petroleum-based materials for single-use packaging material applications. The main weakness of TPS is sensitive to water and humidity which causes low mechanical properties and low thermal resistance. To address this limitation, one can enhance the strength is by incorporating cellulose nanofiber as a reinforcing agent. Cellulose nanofiber used in this study is bacterial cellulose, synthesized from tapioca liquid waste media, namely Nata de Cassava (NDCass). The effect of NDCass addition to TPS on chemical characteristics, physical properties, crystallinity, mechanical properties, and thermal properties was investigated. As the results, NDCass incorporation has no significant effect on the chemical structure and crystal structure of composites as observed by FTIR and XRD analysis. Incorporating of NDCass improved the mechanical properties by 37.3 %, the thermal stability, and the viscosity, however reduced the elongation at break by 65.6 %, the density, the melt flow and shear rate of TPS composite. This study evidently that starch from Arenga pinnata trunk and bacterial cellulose from tapioca liquid waste can be manufactured into biocomposites using in-situ twin screw extrusion which beneficial for large-scale applications.