During the summer months, Madrid endures extreme heat. These high temperatures strain both the infrastructure supporting the city and the well-being of its inhabitants, disproportionately impacting marginalized populations. Marginalized populations such as the homeless population and inhabitants of “Poblados dirigidos” face heightened risks due to inadequate shelter and limited access to cooling infrastructure. While previous research has addressed the technical dimensions of urban heat mitigation, there is a lack of focus on the socio-spatial inequalities of vulnerable populations regarding urban heat. To address this, the research combines quantitative analysis with qualitative fieldwork. San Cristóbal de los Ángeles was selected as the intervention site due to its socio-economic challenges, historical context, and observed urban heat vulnerabilities. The findings show that the impacts of urban heat are rooted in existing social, historical, and spatial inequalities. Responses include the development of climate shelters that offer relief from extreme heat, as well as its establishment in a broader network that ensures spatial distribution, accessibility, and integration within the city’s existing infrastructure. This study highlights the need to rethink the role of shelter in responding to overheating cities. Addressing Madrid’s urban heat is not solely about reducing temperatures, it is about rethinking the socio-spatial systems that shape its city, ensuring they are inclusive, resilient, and just.