Résumé : This paper analyses a research topic poorly considered by authors interested in the legitimacy of environmental governance, that is to say the dynamics created by its interpretation by private sector actors. In order to fill this gap, a recent decision of the Convention on Biological Diversity (CBD) –decision VIII/17 adopted in Marsh 2006- to further involve the private sector in the activities of the Convention is considered. The legitimacy of decision VIII/17 is twofold. Its first dimension requires the consideration of the impact it has on private sector activities related to the CBD. A multi-dimensional definition of legitimacy – input and output- is used to cover the whole range of possible interactions. The second one is linked to the legitimisation processes it might create inside the business community. This second dimension is crucial as there is a risk to see the decision reinterpreted and bypassed by private actors. The case study demonstrates the complexity of the mechanisms at stake in the involvement of the private sector as well as the diversity of topics that link business to environmental issues. More than outright incompatibility or a situation of domination by one actor over another, there is a whole complex of interactions that contribute to broader biodiversity governance.