With the rapid degradation of biodiversity worldwide, protected areas, especially transboundary ones, represent crucial safe places for wildlife. Through the example of lion conservation and research in the WAP ecosystem, spanning between Benin, Burkina Faso and Niger in West Africa, the current synthesis presents the successes and challenges of the management of a transboundary protected area. The lion, a threatened species in West Africa, has its most viable population in the WAP ecosystem. Since almost two decades, the three countries are working to harmonize their efforts to improve the status of the species. Concerted population monitoring is effective with complementarity in law enforcement. Some challenges remain, highlighting the importance of a concerted and integrated management for the successful species conservation and transboundary protected areas management.