This chapter reviews the Congo Basin’s urbanization focusing on its effects on biodiversity and the environment. An unprecedented rate of unplanned urban growth was one of the clearest patterns to emerge with the majority of people in the Republic of Congo (ROC), Gabon and Equatorial Guinea living in urban areas. The urban population is increasing and will continue to rise in the Democratic Republic of Congo (DRC) and Central African Republic (CAR) in the next decades. Rural populations migrate to urban areas in search of better living conditions. Rapid urbanization and continuous rural–urban migration flow impact biodiversity, the environment and social conditions. Construction and fetching fuel wood clear habitats to support expanding cities whose ecological footprint reaches far into remote areas through bushmeat trade and other commodity demands. Heavily populated urban areas occur in the western Albertine Rift (DRC) and the Douala–Kumba–Bamenda belt through (Cameroon), regions of high altitudes and species richness. Congo Basin’s urban areas are polluted with largely of organic matter waste, but solid waste is also significant. Air quality is below the WHO’s standards in most cities, partly as a result of emissions from obsolete equipment imported from developed countries. Minimal urban planning results in the development of slums in cities; it exacerbates the geohydrological hazards and associated risks. There are significant gaps in urbanization data across the Congo Basin and present challenges to drawing general trends. This review recommends further investment in urban research, planning, implementation of environmental standards and infrastructure development.