Self-constructed cities refer to impoverished neighborhoods that suffer from inadequate housing. Such cities are the result of individual or communal initiatives that must self-construct their neighborhoods. Most of the self-constructed cities are located near endangered bioregions on the Earth, and their continued growth will inevitably aggravate the human impact on our planet. Dwellers in these areas tackle threats such as poverty, environmental degradation, and disaster vulnerability. The lack of knowledge in planning self-constructed cities causes conditions of injustice. However, appropriate management of the existing natural capital of the surrounding areas of such cities can address the mentioned challenges and the conditions for justice. This paper aims to evaluate the role of Nature-Based Solutions (NBS) in planning procedures, to create conditions of fairness and equity in self-constructed cities. The paper focused on the linkage between the application of NBS and four principles of justice: distributive justice, restorative justice, spatial justice, and interactional justice. Considering data from a review of the literature, scrutiny of past planning and policy measures and a field study with interviews with stakeholders, the empirical result of our study delineates important strategic implications of Nature-Based Solutions for sustainable planning in the case study of San José de Chamanga, Ecuador. It was demonstrated how small-scale, natural-based interventions, instead of broader actions based on a pure engineering perspective, are economically and ecologically profitable, with a positive impact on local communities’ well-being and social cohesion.