Floods are one of the most common natural disasters affecting numerous people worldwide. Over the last years, Nature-Based Solutions (NBS) have gained attention as an emerging approach for flood mitigation that can complement traditional grey infrastructures. NBS provide several ecosystem services, including flood mitigation and improved water quality. Increasing political awareness and interest from the scientific community have led to the implementation of NBS worldwide. This contribution provides an overview of the concept of NBS for flood mitigation, focusing on (1) the environmental impacts of NBS, (2) the effectiveness of NBS in flood mitigation based on several case studies, and (3) the socio-economic aspects of NBS. Compiling the latest research, this book furthers our understanding of the role of NBS for flood mitigation and its relation to environmental aspects, to guide students, managers, practitioners, policy-makers, and scientists in future NBS projects.