Niger–Congo is a hypothetical language family spoken over the majority of sub-Saharan Africa. It unites the Mande languages, the Atlantic-Congo languages (which share a characteristic noun class system), and possibly several smaller groups of languages that are difficult to classify. If valid, Niger-Congo would be the world's largest in terms of member languages, the third-largest in terms of speakers, and Africa's largest in terms of geographical area. It is generally considered to be the world's largest language family in terms of the number of distinct languages, just ahead of Austronesian, although this is complicated by the ambiguity about what constitutes a distinct language; the number of named Niger–Congo languages listed by Ethnologue is 1,540.

If valid, it would be the third-largest language family in the world by number of native speakers, comprising around 700 million people as of 2015. Within Niger-Congo, the Bantu languages alone account for 350 million people (2015), or half the total Niger-Congo speaking population. The most widely spoken Niger–Congo languages by number of native speakers are Yoruba, Igbo, Fula, Ewe, Fon, Ga-Dangme, Shona, Sesotho, Zulu, Akan, and Mooré. The most widely spoken by the total number of speakers is Swahili, which is used as a lingua franca in parts of eastern and southeastern Africa.

While the ultimate genetic unity of the core of Niger-Congo (called Atlantic-Congo) is widely accepted, the internal cladistic structure is not well established. Other primary branches may include Dogon, Mande, Ijo, Katla and Rashad. The connection of the Mande languages especially has never been demonstrated, and without them, the validity of Niger-Congo family as a whole (as opposed to Atlantic-Congo or a similar subfamily) has not been established.

One of the most distinctive characteristics common to Atlantic-Congo languages is the use of a noun-class system, which is essentially a gender system with multiple genders.