Yam (Dioscorea rotundata Poir) is a vital staple food in Nigeria and much of Africa, contributing approximately 200 calories per capita. However, its production is constrained by several factors, particularly the handling wounds on yam tubers that serve as entry points for pathogenic rot fungi. This study evaluated the efficacy of oil palm-pressed fibre (OPPF) as a natural biocide to treat wounded yam tubers and prevent fungal contamination. Using a completely randomized design with replicated treatments, the study monitored weight loss and fungal presence over time. No fungal contamination or weight loss was observed in OPPF-treated tubers initially. However, from day 8 onwards, six fungal pathogens—Aspergillus spp., Penicillium spp., Botryodiplodia theobromae, Fusarium moniliforme, Sclerotium rolfsii, and Rhizopus stolonifer—were isolated from both treated and untreated samples. The untreated control tubers exhibited progressive weight losses of 2.09%, 3.70%, 4.19%, 6.66%, 11.97%, and 13.9% over the incubation period. The pathogenic fungi significantly compromised tuber viability, with the highest weight loss recorded at 64.69% due to B. theobromae, Penicillium spp., and Sclerotium rolfsii, and the lowest at approximately 45.5% and 49.87% for Aspergillus spp. on days 20 and beyond, respectively. These results demonstrate that OPPF effectively inhibited fungal contamination on wounded tubers, particularly during the early stages of storage. Based on these findings, OPPF shows promise as a cost-effective and natural biocidal treatment to protect yam tubers from pathogenic fungal rots, thereby enhancing storage life and reducing post-harvest losses.