The Indo-Phil Nickel Corridor emerged from cooperation between the Indonesian Nickel Miners Association, locally known as Asosiasi Penambang Nikel Indonesia (APNI), and the Philippine Nickel Industry Association (PNIA), and was further formalised through a Memorandum of Understanding (MoU) on Strategic Nickel Industry Development Cooperation signed during the 48th Association of Southeast Asian Nations (ASEAN) Summit and Related Meetings in Cebu, Philippines. Employing qualitative document analysis informed by geo-economic regionalism, this study examines how the initiative reconfigures regional cooperation in nickel production and value-chain integration. The findings demonstrate that the Corridor creates opportunities for geo-economic integration through the structural complementarity of Indonesia’s downstream industrial capacity and the Philippines’ upstream resource base, strengthens ASEAN’s collective position within global critical mineral supply chains, and encourages greater convergence in environmental, social, and governance (ESG) standards. However, these opportunities are constrained by structural asymmetries, weak institutionalisation, regulatory fragmentation, environmental constraints, and external geopolitical pressures, including trade disputes and increasingly fragmented compliance regimes. This article argues that the Corridor reveals a fundamental governance paradox: its industry-led business-to-business (B2B) structure provides the flexibility necessary to initiate cross-border cooperation while its institutional informality simultaneously constrains the development of durable regional governance. The absence of legally binding commitments, formal dispute-settlement mechanisms, and harmonised regulatory frameworks limits the Corridor’s capacity to sustain investment coordination, policy continuity, and resilience to political and market disruptions. The analysis therefore suggests that deeper state-level institutional coordination and regulatory convergence are necessary to overcome these limitations, potentially through a gradual transition toward a government-to-government (G2G) framework, although such institutionalisation would also expose the Corridor to greater legal and political scrutiny from external trading partners.