Living-condition deficits remain widespread in rapidly growing cities, yet their spatial distribution is poorly measured beyond metropolitan areas, limiting progress toward Sustainable Development Goal (SDG) 11.1 on adequate, safe and affordable housing. Here we conceptualize morphological deprivation as an area-based form of disadvantage reflected in built form, residential density, road connectivity and infrastructure conditions, and generate globally comparable, neighborhood-scale estimates across 5,132 cities in Africa, Asia, and Latin America and the Caribbean. Using harmonized geospatial datasets and supervised learning trained on eight benchmark cities, we estimate that 395 million people (20.2% of the covered urban population) live in morphologically deprived neighborhoods. While relative prevalence is highest in Africa (43.6%), substantial populations are affected across all regions. Notably, over one-third (136 million) reside in small and medium-sized cities, revealing a large but underrecognized burden and underscoring the need to prioritize these cities in data, finance and policy efforts to achieve SDG 11.1.