Kibera (Kinubi: Forest or Jungle) is a division and neighbourhood of Nairobi, Kenya, 6.6 kilometres (4.1 mi) from the city centre. Kibera is the largest slum in Nairobi, and also the largest urban slum in all of Africa. The 2009 Kenya Population and Housing Census reports Kibera's population as 170,070, contrary to previous estimates of one or two million people. Other sources suggest the total Kibera population may be 500,000 to well over 1,000,000 depending on which slums are included in defining Kibera.

In 2009, a survey conducted by the French Institute for Research in Africa found that the average Kibera slum resident lives in extreme poverty, earning less than US$2 per day. Unemployment rates are high. 12% of the population are living with HIV. Cases of assault and rape are common. There are few schools, and most people cannot afford education for their children. Clean water is scarce. Diseases caused by poor hygiene are prevalent. A great majority living in the slum lack access to basic services, including electricity, running water, and medical care.

The government initiated a clearance programme to replace the slum with a residential district of high-rise apartments, and to relocate the residents to these new buildings upon completion.^[when?]

The neighbourhood is divided into a number of villages, including Kianda, Soweto East, Gatwekera, Kisumu Ndogo, Lindi, Laini Saba, Silanga, Makina, Salama, Ayany, and Mashimoni.

The city of Nairobi, where Kibera is located, was founded in 1899 when the Uganda Railway line was built, thereby creating a need for its headquarters and British colonial offices. The colonial administration intended to keep Nairobi as a home for Europeans and temporary migrant workers from Africa and Asia. The migrant workers were brought into Nairobi on short-term contracts, as indentured labour, to work in the service sector, as railway manual labour and to fill lower-level administrative posts in the colonial government.

Between 1900 and 1940, the colonial government passed a number of laws – such as the 1922 Vagrancy Act – to segregate people, evict, arrest, expel and limit the movement of the natives and indentured workers. Within Nairobi, Africans could live in segregated "native reserves" at the edge of the city. Permits to live in Nairobi were necessary, and these permits separated living areas of non-Europeans by ethnic group. One such group were African soldiers who served the military interests of the British colonial army, and their assigned area developed into a slum, now known as Kibera.

Kibera originated as a settlement in the forests at the outskirts of Nairobi, when Nubian soldiers returning from service with the King's African Rifles (KAR) were allocated plots of land there in return for their efforts in 1904. Kibera was situated on the KAR military exercise grounds in close proximity to the KAR headquarters along Ngong Road. The British colonial government allowed the settlement to grow informally. The Nubians had no claim on land in "Native Reserves" and over time, other tribes moved into the area to rent land from the Nubian landlords. With the increase in railway traffic, Nairobi's economy developed, and an increasing number of rural migrants moved to urban Nairobi in search of wage labour. Kibera and other slums developed throughout Nairobi.

Proposals were made in the late 1920s to demolish and relocate Kibera, as it was within the zone of European residential holdings; however, the residents objected to these proposals. The colonial government considered proposals to reorganise Kibera, and the Kenya Land Commission heard a number of cases which referred to the "Kibera problem". By then, Kibera was not the only slum. A 1931 Colonial Report noted the segregated nature of housing in Nairobi and other Kenyan towns, with housing for Europeans reported as good, and widespread prevalence of slum property for Africans and other non-European migrants.