The Indo-Pacific region is undergoing a profound power transition characterized by China’s rapid strategic expansion and the reconfiguration of maritime geopolitics. As the world’s economic and strategic center of gravity shifts toward Asia, Beijing’s naval modernization, assertive gray-zone tactics, and expansive Belt and Road Initiative maritime projects are challenging the existing rules-based order and reshaping regional power distribution. This article examines the convergence between India and Japan as a critical middle-power response to this power transition. Drawing on Power Transition Theory and concepts of strategic hedging and minilateralism, it argues that India-Japan strategic synergy, manifested through operational naval cooperation, defense technology collaboration, quality infrastructure initiatives, and leadership in the Quadrilateral Security Dialogue (Quad), represents a sophisticated mechanism through which secondary powers can actively influence the emerging regional order without entering formal military alliances. Key findings reveal that while the partnership has achieved notable operational and normative progress by leveraging complementary capabilities and shared visions of a Free and Open Indo-Pacific (FOIP), its effectiveness is tempered by India’s strategic autonomy, Japan’s constitutional constraints, and asymmetric threat perceptions. The article concludes that sustained India-Japan convergence can contribute to a more stable, multipolar Indo-Pacific equilibrium. It offers policy recommendations for deepening technological and operational cooperation among like-minded partners to uphold maritime norms amid ongoing power shifts.