Global urbanization has increased rapidly and it is expected to continue. Due to the continuing urbanization process, green areas are transformed into areas for housing, industry and infrastructure. As a consequence, ecosystems in urbanizing areas are affected, which results in degradation of habitats, due to fragmentation and disturbances, with significant impacts on biodiversity and ecosystem services. In cities, green areas are of primary interest to support biodiversity as well as in their role as producers of ecosystem services; that is, services that ecosystems produce to the benefit of humans often without any costs. In addition, publicly accessible urban green areas enhance life quality for urban citizens. To strengthen biodiversity and ecosystem services considerations in the planning process and contribute to the preservation of biodiversity in the long term, a consistent assessment of potential impacts is required. In particular, a landscape approach in urban planning and assessment is needed to address the scales of ecological processes, to strengthen important landscape structures and functions in urban, regional and infrastructure planning. A landscape approach calls for methods for assessing the impacts of human actions on biodiversity at a landscape level, across administrative borders. Such methods should allow an analysis of cumulative impacts of many single planning decisions. Several of the processes involved have a temporal and spatial dimension and are possible to quantify, analyse, and visualize with geographical information systems (GIS) combined with spatial ecological models. This allows for localization and quantification of predicted effects of urbanization on biodiversity components over landscape and regional scales. This chapter addresses impacts of urbanization on biodiversity and urban green areas’ capacity in providing ecosystem services. A brief description of the role of biodiversity and ecosystem services provides a framework for a landscape approach in biodiversity assessments and for the practical examples from the Stockholm region. Related to the assessment, tools for predicting and assessing biodiversity impacts at a landscape level will be discussed as well as planning and management of urban green areas. The chapter concludes with lessons learned and key recommendations for best practice.