This paper explores how small-scale nature-based solutions (NbS) can encourage coexistence among multiple species by comparing the cities of Singapore and Manizales, Colombia. The study recognises the differences in agency among species and takes a spatial design approach, assessing five dimensions of multi-species spatial integration in urban environments: spatial representation (agency), data collection, ecological indicators, infrastructure metrics, and citizen participation. A normative and policy analysis was performed to evaluate urban planning strategies that incorporate NbS and support multi-species coexistence and agency in both cities. The research employed principles of multi-species studies to explore further interspecies spatial agency, including walking ethnographies, transect surveys, and ecological mapping. Results reveal a consistent gap between official planning narratives and on-the-ground practices, with multi-species considerations often marginalised in formal planning, even where strong green infrastructure exists. Conversely, in areas with limited formal governance, resident-led initiatives foster diverse multi-species habitats, indicating that informal practices can sometimes fill normative gaps. Factors such as open access and proximity to mixed land uses have been shown to enhance ecological health and social engagement. Strategies that recognise the inherent right of natural biodiversity to coexist in urban and non-urban settings are necessary, as they may offer unique perspectives on designing multi-species urban futures. The article presents a flexible, transferable assessment tool designed for the Global South, offering a practical framework to evaluate green infrastructure from the perspective of multi-species coexistence.