Mayoko District is a district in the Niari Department of south-western Republic of the Congo. The capital lies at Mayoko. It has a northern border with Gabon. As of 2007, the population is 5,147.
Mayoko is served by a branch railway of the Congo–Ocean Railway that terminates in Mbinda. It lies near the border with Gabon.
Mayoko is near deposits of iron ore, which are very close to an existing railway line leading to a port.
Coordinates: 02°19′30″S 12°47′51″E / 2.32500°S 12.79750°E