Osun Sacred Forest Grove is a unique landscape that combines important environmental, biological and cultural features. We conducted a multifaceted rapid assessment to evaluate the conservation status of the grove eleven years after it was designated a World Heritage Site. We recorded a rich diversity, consisting of 2 rock types, 3 minerals, 88 plant species, 108 insect families and 4 mammal species. Our survey also enabled us document up to 40 cultural artifacts. However, the plants, small mammals and insects collected, in their role as indicator taxa, demonstrate that biodiversity decreases extending outward from the core area of the grove into the buffer and outside zones. In addition, the detection of heterotrophic bacteria and fungi from microbiological analyses in water samples of the Osun River which runs through the grove raises health concerns. Our findings lead us to recommend that efforts be stepped up to deter encroachment of the buffer and outside zones into the core area of the grove. Furthermore, careful repair of deteriorating cultural artifacts should be undertaken regularly, with the actions of visitors monitored adequately to prevent depletion of biodiversity and pollution of the environment.