This paper analyses the levels and trends of childhood mortality in urban Bangladesh, and examines whether children’s survival chances are poorer among the urban migrants and urban poor. It also examines the determinants of child survival in urban Bangladesh. Data come from the 1999–2000 Bangladesh Demographic and Health Survey. The results indicate that, although the indices of infant and child mortality are consistently better in urban areas, the urban–rural differentials in childhood mortality have diminished in recent years. The study identifies two distinct child morality regimes in urban Bangladesh: one for urban natives and one for rural–urban migrants. Under-five mortality is higher among children born to urban migrants compared with children born to life-long urban natives (102 and 62 per 1000 live births, respectively). The migrant–native mortality differentials more-or-less correspond with the differences in socioeconomic status. Like childhood mortality rates, rural–urban migrants seem to be moderately disadvantaged by economic status compared with their urban native counterparts. Within the urban areas, the child survival status is even worse among the migrant poor than among the average urban poor, especially recent migrants. This poor–non-poor differential in childhood mortality is higher in urban areas than in rural areas. The study findings indicate that rapid growth of the urban population in recent years due to rural-to-urban migration, coupled with higher risk of mortality among migrant’s children, may be considered as one of the major explanations for slower decline in under-five mortality in urban Bangladesh, thus diminishing urban–rural differentials in childhood mortality in Bangladesh. The study demonstrates that housing conditions and access to safe drinking water and hygienic toilet facilities are the most critical determinants of child survival in urban areas, even after controlling for migration status. The findings of the study may have important policy implications for urban planning, highlighting the need to target migrant groups and the urban poor within urban areas in the provision of health care services.