The paper aims to develop a decision tool for planning offshore wind farm locations, combining multi-criteria decision analysis and geographic information systems. This method considers several technological, environmental, social, and economic criteria. The criteria are used as evaluation factors and constraints to rank the identified potential locations through an Analytic Hierarchy Process. During the evaluation of the available areas, a pairwise comparison is used in which a group of experts determines the weights. Sensitivity and consensus analyses evaluate the results robustness. The methodology is developed for a case study in the Atlantic coastal areas of Portugal, Spain, and France. The results show the potential of this tool to support the planners in the designation of regions for floating wind farm development.