Middle power discourse has long been Western-centric with a greater focus on capacity, positionality, liberal behaviour, identity and regionalism, wherein states like Australia and Canada were prominent in these studies. With the Asian Century on the rise, middle powers in the Asia Pacific are back in debates on International Relations (IR). The emerging multipolarity reveals the problems of globalization, the weaknesses of multilateral institutions and the growing limitations of systemic powers such as the US and China. These factors have simultaneously led the Asia Pacific's middle powers, including Indonesia, Malaysia, ROK or South Korea, and Vietnam, to take more significant roles, diversify relations, and shape the normative security for long-term peace and stability. This thesis argues for broadening middle power theory to include non-Western ‘Global IR’ frameworks for a holistic understanding of the role of national identities and the complexities of deep pluralism in the politics of the Asia-Pacific region. Using comparative case study research design, this thesis aims to explore the history of ideas, norms and beliefs, national identities, historical endurances, principles, values and modern state interests of Malaysia, Indonesia, ROK or South Korea, and Vietnam in determining their indigenous middle power strategies and foreign policy imperatives. Amidst competition in their geopolitical theatre, there is little to no indication of these states picking any sides. Moreover, the overemphasis on balancing, soft power, and hedging does not entirely capture the security pluralism and normative diffusion in the Asia-Pacific region. Multi-alignment, informality, and complex interdependence have caused a decentralization of the international system. In this regard, middle powers in Asia-Pacific present new opportunities to pursue transcendental institutionalism, globality, and principled and normative diplomacy in the era of complex security pluralism. Further research can be pursued on the securitizing geopolitical risks, globality and plurality, considering the need to constantly re examine middle powerism in the changing international system and order.