Abstract: Evaluating the effectiveness of coastal ecological restoration is essential for coastal ecological protection, as it enables a comprehensive assessment of improvements in nearshore waters and shoreline environmental quality achieved by restoration projects. As a representative coastal ecological restoration project in the Pingtan Comprehensive Experimental Zone, the eastern Pingtan coastal restoration project, focusing on Yufan Bay and Da’ao Bay, has passed project acceptance. However, its ecological benefits have not yet been quantitatively evaluated. In this study, 16 indicators were selected to construct an evaluation system for island coastal ecological restoration effectiveness by integrating the comprehensive index method and the analytic hierarchy process across two dimensions: disaster prevention and mitigation benefit and ecological benefit. Based on this system, an empirical assessment was conducted for Yufan Bay and Da’ao Bay. The results showed that the comprehensive benefit score of Yufan Bay increased from 45.21 to 53.09, while its evaluation grade remained at the moderate level after restoration. In contrast, the comprehensive benefit score of Da’ao Bay increased from 56.69 to 72.36, and its evaluation grade improved from moderate to good. Specifically, the disaster prevention and mitigation benefit of Yufan Bay remained moderate before and after restoration, whereas its ecological benefit improved from moderate to good. In Da’ao Bay, both disaster prevention and mitigation benefit and ecological benefit improved from moderate to good. Overall, the restoration project achieved positive effects in enhancing coastal ecological functions and improving disaster prevention and mitigation capacity, but the magnitude of improvement varied across regions. The findings indicate that the effectiveness of coastal ecological restoration is influenced not only by engineering measures, but also by factors such as regional ecological baseline conditions, shoreline characteristics, and the degree of alignment between restoration objectives and local conditions. Future restoration practice should further optimize restoration pathways in accordance with the dominant ecological problems and spatial characteristics of different bays, while strengthening continuous post-restoration monitoring and dynamic evaluation.