International courts (ICs) have become central to the architecture of global governance. States have empowered ICs to serve several roles in global governance, but at the core, they are “courts” tasked with interpreting and applying the law. Yet, observers of international courts quickly note that ICs are engaging in “judicial diplomacy,” ranging from public relations activities, diplomatic missions to visit national ministries, seeking external funding partners and technical assistance, to name a few. Why is it that international courts have taken on these roles—clearly breaking the ethos of courts which is to be politically isolated and above the fray? This paper introduces the concept “judicial diplomacy, and looks inside international courts to identify their practices of “judicial diplomacy.” The paper offers an explanation for why international courts engage in judicial diplomacy, arguing that ICs use judicial diplomacy as a means of strategic legitimation. They seek to improve public perceptions of ICs and boost institutional legitimacy by creating narratives about an IC’s commitment to its founding principles, community values and respect for state consent. I examine this argument in case studies on the African Court of Human and Peoples’ Rights and the European Court of Human Rights. The case studies build on data from official court documentation, speeches, press releases and more.