Nature has provided humankind with food, fuel, and shelter throughout evolutionary history. However, in contemporary cities, many natural landscapes have become degraded and replaced with impermeable hard surfaces (e.g., roads, paving, car parks and buildings). The reversal of this trend is dynamic, complex and still in its infancy. There are many facets of urban greening initiatives involving multiple benefits, sensitivities and limitations. The aim of this paper is to develop a characterisation method of nature based solutions for designing and retrofitting in the built environment, and to facilitate knowledge transfer between disciplines and for design optimisation. Based on a review of the literature across disciplines, key characteristics could be organised into four groups: policy and community initiatives, multiple benefits assessment, topology, and design options. Challenges and opportunities for developing a characterisation framework to improve the use of nature based solutions in the built environment are discussed.