Australia-China relations have been relatively stable over the last decade. However, soon after the outbreak of COVID-19, Australia took an increasingly assertive stance toward China, one that is arguably even more assertive than those of its Western allies. What prompted Australia to adopt a tougher policy against China? This article argues that COVID-19 has brought significant uncertainty to the international system and, hence, to Australia's external environment, which has affected the country's decisionmaking, accelerating the formation of a hardline policy toward China. A contributing factor behind this policy is Australia's quest for ontological security, which, in the context of COVID-19, has triggered a rise in anti-China sentiment. Meanwhile, this strategy backfired when it encountered China's own nationalism, which exacerbated the widening political chasm, dragging the two countries into an unprecedented diplomatic confrontation. The core of ontological security lies in maintaining the stability of the identity needed for the formation of consistent policy. The uncertainties created by the COVID-19 pandemic have changed the familiar external environment and challenged Australia's ability to interpret this new environment and adjust to it, which has triggered ontological insecurity. By analyzing Australia's identity as a middle power in the context of changing regional security and its commitment to certain values, the article shows how COVID-19 has accelerated Australia's quest for ontological security, which has changed the country's China policy.