Cities are increasingly adopting Nature-Based Solutions (NBS) to address multiple societal challenges effectively. Successful adoption of NBS and realization of their multifunctionality requires a holistic and collaborative planning approach that incorporates stakeholders across scales and disciplines. However, such an approach is usually not aligned with the mainstream sectoral planning process in cities. Planning support systems (PSS) play an essential role in the transition to collaborative planning. Current systems used for NBS planning tend to be highly specialized, focusing on a few ecosystem services and a single scale. As a response, the NBS-PSS is introduced. This system's novel multiscale hierarchical framework helps stakeholders to prioritize sites and solutions in an integrative manner. The NBS-PSS provides the flexibility needed for NBS planning and allows users to interact and iterate over different planning process stages. The system has been tested in the city of Eindhoven with a group of experts. Accordingly, the system appears to have a high capacity to facilitate collaboration and motivate stakeholders to engage in the planning process, given the rapid responses and easy-to-understand process and data representation. Moreover, the NBS-PSS was found to be a helpful tool for enhancing the awareness of opportunities for NBS in urban settings.