Australia’s Constitution has been shaped by a blend of legal and political constitutionalism; yet there is limited attention given to political mechanisms of control in Australia. With the recent developments in the United Kingdom and the turmoil of Brexit that shifted the balance between legal and political constitutionalism, it is timely to examine how political constitutionalism has evolved in Australia. This article argues that Australian political constitutionalism is distinct from the United Kingdom as it is shaped not by internal conflict about the nature of the constitution but rather by the significant evolutionary development of fundamental institutions. In particular, it is argued that there are three critical junctures for political constitutionalism in Australia: the foundations of the Commonwealth, the formation of disciplined political parties and the rise of oversight bodies. It is contended that Australia may be reaching a new critical juncture due to the fragmentation of responsible government from privatisation and outsourcing and the rise of ministerial advisers.