In recent years the concept of industrial symbiosis has been recognized as one of the most effective principles of the circular economy, with a positive impact on the environment on one hand and contributing to economic benefit on the other. The major role of spatial planning is to guide and coordinate different interests in the physical space and direct them in accordance with spatial planning procedures and methods. In addition to engineering, spatial planning is also recognized as a political and governmental discipline, where physical space represents the “arena” for arrangements of different activities and actions. Spatial development plans represent the legal instruments enabling the development and integration of industrial symbiosis alongside other contemporary trends in cities. In Slovenia, the potentials of industrial symbiosis are recognized only on the national level as a development axis. However, there is a lack of integration of the concept into spatial development strategies, programs and plans on the regional and local level. The concept is developed only on the level of waste management, which is based on the recycling of general household waste and not based on the exchange of waste as raw material between different industries. The main aim of the paper is to develop a methodology for integrating industrial symbiosis into spatial development plans on the strategic level. Since the City of Ljubljana is highlighted as one of the drivers of the circular economy in Slovenia, the paper will present Ljubljana as a case study of the research. The methodology will be developed based on research of the relationships between industrial symbiosis and spatial development plans and analysis of spatial development strategies, programs and plans to find the potentials for integrating a new model, industrial symbiosis, into the spatial planning system in Slovenia, which could enable a platform for the development of the circular economy.