Rusizi is a district (akarere) in Western Province, Rwanda.

Its capital is Kamembe, the major city of the Rwandan south-west and the district contains large parts of the former Cyangugu Province.

Rusizi's capital, Cyangugu, is one of the three major Rwandan lake ports of Lake Kivu (along with Kibuye and Gisenyi) and it contiguous with the much larger Congolese city of Bukavu.

The district also contains the western half of Nyungwe Forest, a popular tourist destination, being one of the last remaining forest areas of Rwanda and home to chimpanzees and many other species of primate.

Rusizi district is divided into 18 sectors (imirenge): Bugarama, Butare, Bweyeye, Gikundamvura, Gashonga, Giheke, Gihundwe, Gitambi, Kamembe, Muganza, Mururu, Nkanka, Nkombo, Nkungu, Nyakabuye, Nyakarenzo, Nzahaha, Rwimbogo.