Forest fires have caused irreparable environmental and economic losses in all around the world due to global warming. In order to take necessary measures and make fire prevention and response strategies, forest fire risk assessment is curial. This study aims to make forest fires risk assessment in the largest forest area in Istanbul, Turkey. Fire risk assessment was carried out by integrating Multi-Criteria Decision-Making (MCDM) methods and Geographical Information Systems (GIS). The criteria weights were calculated using the Analytical Hierarchy Process (AHP) and Fuzzy Analytical Hierarchy Process (Fuzzy AHP) methods. Forest fire risk assessment was carried out in the Geographical Information Systems (GIS) environment by using the required data and calculated criteria weights. It is found that although the fire risk limit values differs in some areas, the evaluation results based on the AHP and Fuzzy AHP methods overlap to a large extent. The AHP and Fuzzy AHP methods provided valid, reliable and very useful results in the forest fire risk assessment. This study shows that integrating the AHP and Fuzzy-AHP methods with GIS for forest fire risk assessment provides very important guidance in making the necessary planning and taking measures for forest fires.