While there are contemporary signs of ‘authoritarian pushback’ eroding global governance in the ‘liberal’ world, the converse seems to be happening in ‘soft authoritarian’ Southeast Asia. Since the ASEAN Charter (2007), ASEAN members have strived to reform their intergovernmental grouping into a formal rules- and institutions-based regional organization that stands credibly in the international legal order. Informed by rationalist-institutionalist principles, this paper examines ASEAN’s motives in becoming a rules-based Community; the correlation between general concepts of legalization and institutionalization and ASEAN’s ambition; and the critical challenges (e.g. the staunch state-centric, authoritarian outlook) that impede transformation. While it is unlikely ASEAN members would ever become ‘liberal’ states, there are key changes that would help realize their collective ambition for the organization whilst retaining an indisputably intergovernmental ASEAN in form and function.