The international politics of biodiversity are now known to encompass several international institutions. This phenomenon has been recently analysed as a “regime complex”. While the biodiversity regime complex is one of the most established one, studies have tended to favour the qualitative analysis of its core elements (the Convention on biological diversity (CBD), CITES, etc.), instead of capturing the overall architecture of intergovernmental biodiversity governance. To fill this gap, this paper investigates the external and internal links that the core institution of the biodiversity regime complex (the CBD) has drawn and is drawing with other intergovernmental institutions. The external links are studied by analysing all the intergovernmental institutions that asked and obtained an observer status to the CBD negotiations. The internal links are studied by analysing all the partnerships that the CBD has developed with other intergovernmental organisations. After presenting general statistics on both observers and partnerships over the period 1992-2018, the communication comments qualitatively the characteristics of such links. Analysing the links helps us identify the elements of the international architecture on biodiversity that could be adjusted: new links to create, reinforce or soften. This helps assess in which ways biodiversity governance could be transformed to improve its efficiency. The paper importantly contributes to the architecture debate by using the literature on regime complexity and fragmentation. It focuses on a relatively under-researched part of global environmental governance, namely the biodiversity regime complex. Such a mapping exercise of the relationships between the main regimes is needed for better global governance.