As a crucial basis for protecting maritime investments, the application ratione materiae of international investment agreements to investments in disputed waters depends on an assessment of the treaty’s territorial definition clauses and whether the host State exercises jurisdiction over the investment activities. Once such disputes enter judicial proceedings, significant uncertainty arises in practice regarding whether arbitral tribunals can exercise jurisdiction and how to determine the scope of investment protection obligations. China should attach greater importance to the protection of investments in disputed waters and, guided by “maritime community with a shared future,” work to improve its international investment agreements and promote rule-making. This would not only safeguard China’s maritime investment interests but also support its broader goal of participating in and leading global ocean governance.