The scope of this article is to present an index developed to assess the vulnerability to coastal flooding of urban areas which house major industrial activity. Coastal flooding can be a threat to life and to socioeconomic and environmental assets, while the additional impacts of an industrial accident due to coastal flooding may aggravate relevant risks. Therefore, there is a need to integrate tools able to consider, at different complexity levels, the interactions between various parameters in order to effectively assess the vulnerability of such areas. This paper illustrates the development and use of a composite vulnerability index in the risk assessment process, encompassing indicators relevant to the industrial activity. In addition, the paper suggests the differentiation of the relative importance of the considered indicators through a weighting procedure. Usually, the indicators used to create such a composite index are averaged, since decision makers confronting the ambiguity of complex phenomena are reluctant to articulate subjective weights. The novelty of the proposed approach is the use of the CRiteria Importance Through Intercriteria Correlation (CRITIC) method to extract objective weights of the information carried by each indicator in the specific research context. The application study refers to six urban areas with strong industrial characteristics in Greece. The results have been used for comparing and ranking the study areas according to the calculated indices, as well as to highlight the parameters affecting vulnerability in each case.