Urban informal settlements are rapidly expanding in countries around the world. This is due partly to high birth rates, but also because of growing in-migration driven by climate change impacts affecting rural populations. Urban informal settlements struggle with degraded and sometimes nonexistent infrastructure (such as water, sewage, and drainage systems) and service provision (health, education), and these shortcomings are aggravated by urban climate-related hazards like flooding and heat spikes. As informal settlements expand, their already overburdened infrastructure can lead to urban disasters such as flooding and landfill collapse. These challenges increase the governance and financial problems already faced by cities and create significant problems for climate resilience planning processes. Policy responses at both the national and city levels promise much but deliver little. This article reviews what is known about the environmental problems of informal settlements, particularly those in African cities, and how city governments have responded to those problems. We focus on two inland cities: Addis Ababa, Ethiopia, and Kampala, Uganda. We find that city climate adaptation plans do not incorporate the perspective of migrants, who are both particularly vulnerable to climate change and play a role in exacerbating environmental challenges in cities.