Tamsui River Estuary mangrove forest is located adjacent to the Taipei Metropolitan area, where the river meets the ocean. The Greater Taipei area is Taiwan’s largest metropolitan area with a population of over 7 million. Following successive designations of several mangrove forest reserves in the 1980s, the mangrove area of Tamsui River Estuary mangrove forest now exceeds 108 hectares, making it Taiwan’s one of the most important sites for environmental education and research. Mangroves are generally considered to perform critical ecological functions, such as water purification and tidal impact reduction. However, only a few studies have assessed the ecosystem services of mangroves at the Tamsui River Estuary. This study highlighted the mangroves and their relationship to the fringes of Taipei City to assess the ecosystem services provided by the catchment area. The study found that the mangroves have transformed from a wasteland into a mangrove ecosystem, which was familiar to, recognized and protected by citizens and institutions and providing additional cultural services to people. Mangroves are important patches that provide downstream ecosystem services affected by upstream land use changes within the watershed. The government undertook intensive regulatory measures to preserve the environmental quality of the watershed and improve ecosystem services. In this sense, urban mangroves are deeply influenced by urban resilience goals with judgments from multiple perspectives.