This study examines the constitutional and social challenges of prior consultation and citizen participation in Ecuador’s urban infrastructure projects, assessing their implications for sustainable development. The 2008 Constitution establishes a participatory framework that guarantees citizen involvement, mandates environmental consultation, and recognizes the rights of nature. Yet, in urban contexts, these mechanisms often operate as formalities without binding effect, limiting their capacity to influence planning outcomes. Adopting an interdisciplinary socio-legal approach, the research analyzes their practical implementation in large-scale projects, evaluating their alignment with the right to the city and principles of urban sustainability. The findings reveal structural obstacles: absence of a defined procedure for urban consultation, weak enforceability of participatory outcomes, and insufficient integration of environmental and social criteria into municipal planning. Comparative insights highlight that meaningful participation depends not only on formal recognition but also on institutional capacity, transparency, and procedural embedding. The study concludes that, despite strong normative potential, Ecuador’s framework will remain a symbolic promise unless binding consultation, coordinated governance, and institutional reform are enacted to turn constitutional rights into tangible, enforceable urban policies.