The main purpose of a planned construction project is the completion of targeted productions under specified constraints. For this purpose, a wide variety of organizations take place inside and outside of the construction site. Depending on the diversity and complexity of the organizations, the quality and efficiency of the work are directly affected. Achieving the goals of the construction site under various constraints gives workflow and planning prominence. With good planning, the workflow can be provided and the quality of the organizations within the construction site increases depending on this workflow, because efficient planning starts with the installation of the construction site. Mobilization, which means construction site installation, is critical for an efficient construction site. The mobilization plan, which is prepared for taking the construction site and all other criteria into account, is regarded as the first step for a planned construction site. Computer-aided systems are used in many fields with developments in recent years. GIS (Geographical Information Systems) has the potential to generate new information from location data. In this study, a decision support system has been developed utilizing GIS for mobilization, which is critical for construction site efficiency. In this regard, the "Weighted Overlay" plug-in within the ArcGIS software, which is one of the GIS tools, has been used as an auxiliary tool in the site selection of temporary facilities which will be set up in mobilization, as well. In the final stage, a mobilization plan was prepared for a construction site selected for the case study.