Green infrastructure (GI) is planned at various scales, including a regional one: city-regions. Strategic GI planning included in the city-regions spatial development policy can contribute to their sustainable development through, among others, providing a range of ecosystem services. In order to meet the challenge of planning GI on a regional scale, the authors present the Method of Landscape-Functional Units (Method LaFU), which is used for the planning and evaluation of such systems. This method was tested in the Wrocław Functional Area (WFA), which is characterized by many negative processes, primarily uncontrolled development of built-up areas, fragmentation of landscape, and declining natural and semi-natural areas. The presented results show the effectiveness of the Method LaFU in GI planning and, above all, in its assessment, which makes it possible to identify problem areas that are at risk but still important for the functioning of the GI system. This allows for quick decision making by entities responsible for spatial planning in the region. The proposed method can also be used in other city-regions.