<p>Blue carbon projects (BCPs) have significant potential for climate mitigation and sustainable development; however, they often face underinvestment. This research aims to address this challenge by employing a tripartite evolutionary game model to analyze the strategic interactions among local governments (LGs), carbon sink development firms (CSDFs), and financial institutions (FIs). Furthermore, we conduct stability analysis and numerical simulation to identify the key factors influencing the adoption and support of BCPs. Our results indicate that the decisions of CSDFs are primarily sensitive to development costs, technological capabilities, and risk-return profiles. In contrast, FIs’ engagement hinges on government incentives and their own cost–benefit assessments. Moreover, strategic public financing is crucial. LG subsidies directly enhance CSDF’s willingness to participate. Furthermore, LGs must provide compensatory incentives to offset the high costs of financial support to leverage private capital from FIs. Our case study of the Zhanjiang Mangrove Afforestation Project confirms that a synergistic policy package—combining government incentives, financial support, and robust risk and ecological benefit management—can successfully align stakeholder interests and facilitate project implementation. This research provides a theoretical foundation and practical policy insights for designing effective mechanisms to promote blue carbon development.</p>