Within most major metropolises, public authorities are developing strategies to promote biodiversity, with a view to strengthening natural spaces in the urban fabric or to renaturalizing artificial spaces. The PGM, Greater Paris Metropolis, created in 2016, brings together the Paris municipality and more than 130 other municipalities in a territorial establishment responsible for urban planning. The analysis of the interviews with 21 elected representatives of the PGM suggests that biodiversity is a leverage favorable to the flourishing of this Greater Paris in the form of a double ecological frontier. Biodiversity is the subject of special attention due to a shared recognition of its ecosystem services and public policies integrate biodiversity as a structuring element in urban renewal projects within the PGM.