The susceptibility of wood to deterioration from different organisms and its longtime effects on the global economy is enormous. One important aspect of alternative preservatives is bio-preservative plants in which locally available plants or their parts can be used. These are economically viable and environmentally friendly. This research was undertaken to establish the potency of extracts from Euphorbia hirta on the preservation of Ceiba pentandra wood against the strains of white rot fungi (Pleurotus ostreatus) .The stems of E. hirta used for this study were harvested within the University of Ibadan, Nigeria, and identified at the Department of Botany of the University. The crude extraction process was gotten by using water (un-boiled, boiled) and ethanol. The wooden blocks of 2.0 cm × 2.0 cm × 2.0 cm prepared were soaked in the crude extract for 8, 16, and 24 hours. After the treatment, the blocks were then conditioned for 72 hours and then reweighed to determine the retention of the extract. The test samples were inoculated using white rot fungi (Pleurotus ostreatus). It was exposed to a susceptibility test for 12 weeks. A 3×3×6 factorial in a complete randomized block design was adopted for the experiment. The obtained data were subjected to analysis of variance (ANOVA). DMRT was used to determine the significance of the treatment means at α 0.05. The findings indicated that Un-boiled aqueous extract had the highest retention (2.71 kg/m3), and lowest weight loss (2.32%), It also, exhibited the highest inhibitory potency against white rot fungi, followed by boiled extract (1.18 kg/m3) and ethanol extract (1.30 kg/m3) after the six weeks of inoculation. Therefore, the study established that the stem extract of Euphorbia hirta has antifungal activities against white rot fungi isolates and could be a suitable bio-preservative for the control of fungi attack in wood.