Transitional justice, like other peacebuilding endeavours, strives to create change in the world and to produce knowledge that is useful. However, the politics of how this knowledge is produced, shared and rendered legitimate depends upon the relationships between different epistemic communities, the way in which transitional justice has developed as a field and the myriad contexts in which it is embedded at local, national and international levels. In particular, forms of ‘expert’ knowledge tend to be legal, foreign and based on models to be replicated elsewhere. Work on epistemic communities of peacebuilding can be usefully brought to bear on transitional justice, speaking to current debates in the literature on positionality, justice from below, marginalisation and knowledge imperialism. This article offers two contributions to the field of transitional justice: (1) an analysis of the way the field has developed as an epistemic community(ies) and the relevance of this for a politics of knowledge; and (2) an argument for the politics of knowledge to be more widely discussed and understood as a factor in shaping transitional justice policy and practice, and as a call to a more ethical relationship with the supposed beneficiaries of transitional justice interventions.