Bio-mediated soil stabilization is a growing discipline within geotechnical engineering. In recent years, research in the use of biopolymers and fungi has risen in popularity. Using these biomaterials has shown a positive impact in improving the characteristics of the soil. However, they do come with their respective limitations. To overcome their individual limitations, an investigation towards a bio-composite between the two biomaterials was conducted. This study used xanthan gum as the biopolymer and a combination of Rhizopus oligosporus and Rhizopus oryzae (ROO) as the fungi and examined their effects on the soil’s compressive strength. The results showed that the bio-composite yields a significantly higher compressive strength compared to the samples treated with the individual biomaterial. Peak strength was achieved with 10% ROO, 1.5% xanthan gum, and 15% water content after 21 days of curing. As both biomaterials need water to fully develop, it is reasonable to expect a higher water content compared to an individually treated sample. The strength increase could be attributed to the fungi and biopolymer coexisting within the soil’s microstructure as indicated by the scanning electron microscope imaging.