Trees are seen as obstacles of development in the developing countries. Despite global recognition of the role of forests in mitigation of climate change, deforestation and forest degradation continues to increase. However, there is dearth of information on the impact of situating University of Ibadan International Conference Centre (UIICC) on the University’s Tectona grandis plantation. Hence, provision of baseline information on the impact of the Conference Centre on the environment will help management decisions on mitigation of its negative effects. Environmental impact assessment of UIICC on the adjoining forest was conducted. The data used for this study was obtained from all living T. grandis (332 trees) found within seven randomly laid sample plots of 25 m × 25 m. Diameters at several points of tree stems and height (total and merchantable) were measured. Hence, biomass of each sampled tree was estimated. Point coordinates were also obtained to map out the boundaries of the various land cover within the study area. The impact assessment results revealed that about 7066 trees with merchantable volume of 601.55 m3 and total volume of 1266.58 m3 were removed for building of UIICC covering about 9.309 ha. About 274.99 t C and 1009.28 t CO2 e carbon and carbon dioxide, respectively were loss. Furthermore, loss of biodiversity and habitat for animals (birds, reptiles and rodents) and disruptions of biogeochemical cycles were among the identified negative impacts. Planting of avenue trees within the conference centre, proper waste disposal and use of renewable energy were recommended as mitigation measures.