Security plays a pivotal role in the phenomenon of small state-middle power interactions. Given this paradox of the long-standing bilateral relationship between Malaysia and Australia in the broader Indo-Pacific, the security interdependence is nevertheless often overlooked. Primarily, this paper aims to discuss and analyse the interplay between small state and middle power in securitising the existential and emerging conventional and unconventional issues that pose to their national security. To locate the research objective, Regional Security Complex Theory is ultilised as theoretical framework. Multiple qualitative research methods are used to arrive the findings, include collection of primary and secondary data, in-depth interviews with purposive sampling of informants, and analysis of data by using thematic analysis approach. The findings of this paper argue that both Malaysia-Australia bilateral relationship is fundamentally motivated by security interdependence since both states posit within the same regional complex in the broader Indo-Pacific. The security issues are associated with conventional and unconventional security threats. The small state-middle power security interdependence emanated from the historical development of both states. Hence, an 'agreement' is formed by both securitising actors in addressing their security concerns in the military, political, economic and societal sectors.