Kasaï-Oriental (French for "East Kasai") is one of the 21 provinces of the Democratic Republic of the Congo created in the 2015 repartitioning.

[2] Kasaï-Oriental was formed from the Tshilenge district and the independently administered city of Mbuji-Mayi which retained its status as a provincial capital.

Friction with Congo's other ethnic groups and encouragement by Belgian corporations hoping to keep their mining concessions led to the secession of the province of South Kasai as a separate state headed by Albert Kalonji.

The population of Mbuji-Mayi grew rapidly with the immigration of Luba people from other parts of the country.

The region in which Mbuji-Mayi is situated annually produces one-tenth in weight of the world's industrial diamonds, with mining managed by the Société Minière de Bakwanga.