Liberal democracies and illiberal regimes alike recognize academic freedom as a norm that enables scientific progress. This article investigates the extent to which the globalization of academic freedom has been the result of a global diffusion process in addition to national developments, such as modernization and democratization. Academic freedom spread as part of a wider liberal script after World War II. The empirical analysis shows, however, that the codification of academic freedom at the international and regional level has been slower compared with other parts of the liberal script. To the extent that academic freedom has emerged as a global norm, it has happened through decentralized diffusion processes driven by higher education institutions and civil society networks. Different views on meaning, scope and emphasis made international and regional institutions norm takers rather than norm shapers. They only started to systematically institutionalize academic freedom into the liberal script when networks of scholars and higher education institutions mobilized internationally amidst increasing contestations of their academic freedom since the turn of the millennium.