The Convention on Biological Diversity (CBD) the main international environmental agreement (IEA) for securing our planet's life-supporting systems is far from delivering its commitments: the 2010 Biodiversity Target was not met, and states are already failing to achieve the Aichi Biodiversity Targets by the 2020 deadline. Whilst this is not an uncommon outcome in IEAs and other internationally adopted environmental goals, the important question is: how to transform this situation? Review processes on implementation of international norms are one important means for this, as resulting information has potential to mobilise criticism, praise and/or feedback from peers and civil society organisations. Criticism may in turn put pressure on and/or encourage states to justify their behaviour and to take actions. In this context, beyond normative considerations as a practice of good governance, accountability is conceptualised as an active practice of giving and demanding of reason of conduct with transformative potential. Our starting argument is that review processes that enable account-holding dynamics have potential to promote implementation of IEAs. In order to assess whether the CBD enables such dynamics, we characterise the CBD's review system, and analyse its review mechanisms from the relational perspective of accountability. In particular, we focus on a novel voluntary peer-review mechanism (VPR) that is to be applied in a pilot phase, as requested by the Conference of the Parties at its thirteenth meeting held in December 2016. We then discuss the potential of the VPR to enable transformative accountability dynamics and enhance national implementation in the CBD.