The present research aims to analyse the vulnerability of the coastal zone of the Maranhão Legal Amazon (MLA) to rising sea levels resulting from climate change and the contribution of the local mangrove forest to reducing this risk. The MLA coastline is made up of many ecosystems, such as Ramsar sites and approximately 47% of Brazil's mangrove areas (about 460,745 ha); changes induced by human action can affect essential services provided by these ecosystems in the study area. In this research, two computational models are used to estimate the vulnerability of the Maranhão coastal zone to climate change; the first is the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) to assess coastal vulnerability, the second is “BR-MANGUE” to simulate the response of the mangrove to rising sea levels. The results highlight the importance of all coastal ecosystems and the possible damage resulting from their losses, especially in the loss of mangrove areas on the MLA coast. The results also indicate that the protection provided by coastal ecosystems is highly relevant to proposing nature-based solutions to combat the impacts of climate change on the Amazon coastal zone.