Abstract: Current practice in assessing marine environmental quality relies primarily on seawater quality standards and uses a single-factor assessment method. However, this approach often struggles to comprehensively reflect the current status of marine ecological environments and the effectiveness of management and restoration efforts. To scientifically assess the current status and improvement of marine ecological environments and promote innovation in assessment methods and management systems, we take the object as a case study on the coastal areas of Zhejiang Province. From the perspectives of environmental quality, governance effectiveness, and public welfare, 37 indicators were selected, including water quality, shoreline quality, habitat quality and biodiversity and so on. A novel marine ecological environment evaluation system, called “blue ocean” index, was developed using the Analytic Hierarchy Process. The evaluation of the marine ecological environment in five cities along Zhejiang coast showed that Jiaxing had the lowest score (63.3) among the five cities, significantly different from Taizhou (82.9), Ningbo (82.0), Wenzhou (81.7), and Zhoushan (79.6) from 2010 to 2021. The city governance effectiveness scores evaluated were relatively high in the past years, and the public satisfaction scores had significantly increased over the past decade. The evaluation results also indicate that there was still room for improvement in the biodiversity and habitat quality of the Zhejiang coastal region.