The root soil interface harbors complex microbial interactions that influence plant and soil health. A better understanding of using of biochar derived from different waste sources with Trichoderma spp. (TRI), and the relationship between plant disease and environmental parameters would assist setting priorities. Here, we hypothesized that biochar and TRI could be useful in managing cassava root rot, by mainly altering soil properties and their interactions. This hypothesis was tested by assessing the severity of plant disease and soil parameters using biochar derived from four sources (coffee grounds-CG, coffee husks-CH, bean husks-BH, and soursop residue-SW). Our analysis revealed that all TRI-inoculated biochar applied to the soil decreased cassava root rot severity, which was attributed to changes in soil parameters such as pH, P, K, and total organic carbon. Additionally, SW + TRI reduced the severity in shoots by 75% and increased beta-glucosidase (109%) and urease (200%) enzyme activities, thereby reducing cassava root rot severity, which contributed to plant growth and improved soil; hence, this biochar can be recommended in controlling this disease. Overall, our findings expand our knowledge about the reuse of wastes transformed into biochar, which could serve as an alternative tool for plant disease management and provide important information to develop strategies that can be incorporated in the global health concept.