This paper explains why the Association of Southeast Asian Nations (ASEAN) needs its centrality in Indo-Pacific (IP) geopolitical discourse. The “centrality” here refers to ASEAN member states’ concordance with the ASEAN Outlook on the Indo-Pacific (AOIP), aiming for ASEAN’s leadership in promoting their vision on IP geopolitics and its following regional order. By using “constructivist geopolitics” and strategic narrative analytical frameworks, this paper argues that the normative structure of international relations in Southeast Asia (SEA)—consisting of the historical entanglement of SEA’s geographical reality, ASEAN, and the “ASEAN Way”—has incarnated into an (institutional) strategic narrative called AOIP. This new institutional strategy redefines what the IP region means for ASEAN member states and reasserts their ideals on regional governance according to ASEAN centrality. As an implication, IP geopolitics will reproduce the initial SEA’s normative structure. Such perpetuation establishes a new geopolitical (counter)-discourse on IP against dominant ones from external actors (e.g., Australia, China, India, Japan, and the US) and creates a sort of geopolitical system that respects ASEAN’s “sphere of influence” as the “core” and external actors’ “peripherality” within IP. This study contributes to the academic debate on ASEAN’s institutional strategy by offering a new perspective on IP great power politics dominated by non-ASEAN policy discourses and neorealist perspectives in international relations academia.