The Great Rift Valley is a series of contiguous geographic trenches, approximately 7,000 kilometres (4,300 mi) in total length, that runs from Lebanon in Asia to Mozambique in Southeast Africa. While the name continues in some usages, it is rarely used in geology as it is considered an imprecise merging of separate though related rift and fault systems.

This valley extends northward for 5,950 km through the eastern part of Africa, through the Red Sea, and into Western Asia. Several deep, elongated lakes, called ribbon lakes, exist on the floor of this rift valley: Lakes Malawi, Rudolf and Tanganyika are examples of such lakes. The region has a unique ecosystem and contains a number of Africa's wildlife parks.

The term Great Rift Valley is most often used to refer to the valley of the East African Rift, the divergent plate boundary which extends from the Afar Triple Junction southward through eastern Africa, and is in the process of splitting the African Plate into two new and separate plates. Geologists generally refer to these evolving plates as the Nubian Plate and the Somali Plate.