As developing dynamic regions, coastal areas have a high potential for environmental incidents, especially chemical spills, which may permanently threaten livelihoods and coastal ecosystems. Establishing an appropriate methodological framework for assessing environmental incidents in coastal areas, ensuring increased predictability and minimising potential consequences is a trend of interest to scientists. In this study, the environmental risk assessment model was applied to develop a framework for assessing environmental incidents in coastal areas due to chemical spills from the mainland based on hazard, exposure and vulnerability factors (i.e., sensitivity and adaptability). Using the multiple criteria decision-making (MCDM) method approach, suitable criteria, their optimal weights and the risk factors were determined. Modelling, remote sensing, and geographic information system (GIS) methods were used simultaneously for data collection, evaluation, and mapping. A case study was conducted in the coastal area of southeastern Vietnam, which comprises 27 subregions. These were classified into four environmental incident levels: low, medium, high, and extreme. Their prevalence was 70.37%, 3.70%, 7.41%, and 18.52% in the rainy season, and 74.07%, 7.41%, 7.41%, and 11.11% in the dry season, respectively. Based on analysis results and consultation with managers and experts, pertinent and practical solutions were proposed to reduce the risk of environmental incidents in subregions with high and extreme incident levels. Our results are expected to support policymakers in decision-making related to the sustainable development of the study area and complete the methodology framework for assessing environmental incidents in coastal areas due to multiple hazards.