In Tanzania 80% of the population live in informal settlements. Most of these settlements are built in areas that are susceptible to extreme weather conditions such as flooding. Such conditions have significantly contributed to the destruction of housing stock and other valuable properties. There is considerable awareness amongst people living in the informal settlements, government representatives and other key stakeholders about the various flood risks affecting informal settlements. Based on this understanding, several attempts to minimize flood risks have been initiated in Dar es Salaam, Tanzania yet these initiatives have largely failed to deliver the desired impacts. This article aims to investigate core reasons for this through a case study of Keko Machungwa informal settlement in Dar es Salaam City. The study explores the extent to which mainstreaming of disaster risk reduction (DRR) in housing development in informal settlements has been considered and implemented; and recommends measures for improvement. Key methods employed for the research included physical observation, household interviews, mapping, photographing, and in-depth interviews. Overall, the study found that mainstreaming of DRR in housing development was hardly practiced at the household level, as houses are predominantly being built without resistant building materials and supervision of relevant professionals. In order to mainstream DRR in housing development in informal settlements, it is recommended that the government direct its efforts towards regulating, controlling and monitoring the housing development sector by emphasizing the use of flood resistant building materials and establishing resilient infrastructures for flood mitigation in every flood prone informal settlement.