The increasing demand for sustainable materials necessitates advancements in bio-composites with enhanced properties. This study addresses the limitations of Durio zibethinus Murr (DZM) seed starch bio-composites, particularly their poor mechanical strength and thermal stability. Using solution casting, zinc oxide (ZnO) nanofillers and nanocrystalline cellulose (NCC) were incorporated into the starch matrix. The optimized composite with 0.4 g ZnO exhibited a significant improvement in crystallinity (79.40 %), tensile strength (0.44 MPa), and thermal stability (15.54 % residual mass). These findings highlight the potential of the developed bio-nanocomposites for applications in food packaging and medical devices, combining enhanced durability with environmental sustainability.