This article shows how Australian politics played an under-researched part in the development of the Anglosphere idea. By examining the contestation of nationhood in Australia from the republic referendum of the 1990s until the mid-2000s, this article offers a new interpretation of the genesis of the Anglosphere idea. The article suggests that debates about national identity in Australia and the Anglosphere idea are co-constitutive. These co-constitutive relationships are with the United Kingdom (via the republic debate, the process of reconciliation between settlers and Indigenous peoples and civics and citizenship education), New Zealand (via ‘Anzac’ war commemoration) and the United States of America (via defence and security). The Anglosphere idea remains important to debates about national identity and public policy in Australia and provides context for decisions about how Australia positions itself in the world at a time of significant transnational challenges and threats.