This study investigates the causes of homelessness in Lagos Metropolis, Nigeria, with a view to providing evidence-based policy insights that can inform inclusive urban policy and planning interventions. Data were sourced from both the homeless persons and residents living within a 500-metre radius of identified homeless clusters. Convenience sampling was employed to select 188 homeless persons across major markets, motor parks, beaches and transport terminals in selected Local Government Areas (LGAs). On the other hand, systematic sampling was adopted to select 144 residents, drawing from 10% of buildings within the 500-meter radius of each identified homeless clusters. Primary data were collected through questionnaire administration, while secondary data on, number of buildings and maps were obtained from GIS and Cooperative Information Network. Data collected were analyzed using descriptive statistics and narrative analysis techniques. Findings revealed that 36.7% of the sampled homeless person identified unemployment as the primary cause of their homelessness. From the residents’ perspectives, 78.9% of the residents attributed homelessness mainly to poverty. The study concluded that the occurrence of homelessness in Lagos Metropolis cannot be attributed to a single factor, it is driven by a combination socio-economic, psycho-social and structural factors. Therefore, addressing homelessness in Lagos demands holistic strategies that extends beyond provision of immediate shelter but also tackle the systemic inequalities and social determinants that perpetuate housing instability.