This study examines urban planning and the rising prevalence of urban slums in Anambra State, Nigeria from 2015 - 2025. It investigates the extent to which urban planning interventions have addressed housing deficits, overcrowding, and the proliferation of informal settlements within the study period. The research is anchored on Edward Soja’s Spatial Justice theory, which emphasizes the equitable distribution of resources and opportunities in urban space and highlights how spatial inequalities contribute to urban deprivation. A descriptive research design was adopted, relying on secondary data from relevant literature, policy documents, and empirical studies on urban development in Nigeria. Findings show that urban planning efforts have had limited impact on reducing housing deficits, as rapid urban population growth continues to outpace housing provision. It further reveals that while some planning interventions have helped to moderately ease overcrowding, particularly through rural development initiatives and infrastructural expansion, persistent rural–urban migration and weak implementation frameworks continue to undermine these gains. In addition, urban planning measures such as enforcement actions and slum clearance have not significantly reduced informal settlements, as affordability constraints and weak housing policy persist. The study concludes that urban slum growth in Anambra State is driven by structural inequalities in spatial development and inadequate planning capacity. It recommends a more inclusive and justice-oriented planning approach that prioritizes equitable housing provision, infrastructure development, and integration of informal settlements into formal urban systems in line with spatial justice principles.