In the African context, where agricultural by-products and natural resources are often underutilized or considered waste or invasive species, this study aims to valorize locally available raw materials through the development of fully bio-based insulating composite materials. The materials were produced using typha, rice husk, residues from threshing millet ears, and cassava starch, through a simple and reproducible process accessible even at an artisanal scale. A total of 25 formulations were created by combining one to three of these raw materials with a natural binder. The resulting composites were characterized. The bulk density of the materials ranged from 198.64 to 361.02 kg/m3, while their thermal conductivity varied between 0.07 and 0.17 W/m·K. These results highlight the strong potential of these bio-based composites for use as thermal insulation in sustainable building applications.