Material selection for marine environments is an important, difficult, and complex process. For the purpose of decision support, a model was created for the selection of materials for marine environments with the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method, which is used for decision-making in fuzzy environments. The decision criteria in the model were determined by an expert, and according to these decision criteria, alternative materials were evaluated with linguistic variables. In the model, there were four main criteria (corrosion resistance, cost, mechanical properties, and workability) and four sub-criteria (yield strength, tensile strength, hardness, and elongation) under the main criteria of mechanical properties. Alternative materials were ranked according to the criteria and alternative material evaluations which were determined by the expert. The software that the created model was applied, developed in the programming language Visual C#. Thanks to the software, decision-makers can obtain different rankings easily by changing the criteria weights and select material for different environments. In the result of the study, applying sensitivity analysis, impact and priority ranking criteria were evaluated.