Mushrooms are among the most diverse group of living organisms on earth, though inadequately studied worldwide. The objective of this study was to assess the diversity and distribution of mushroom species in riparian zone of Lake Kivu in order to develop a baseline helping for further studies on fungi in Rwanda. The diversity and distribution of mushroom species were studied by plot-based mushroom surveys in Mariri, Mpangara and Nyakarwa sites while a simple random search was used in the garden of the Museum, in different seasons from September 2016 to June 2019. Species similarity between sites was determined using the Sorenson’s coefficients and Chao 2 estimator was used to estimate species richness. Among species collected, Agaricales (81%) is the dominant order in this zone. The total order/family ratio of 0.31, family/genus ratio of 0.65 and genus/species ratio of 0.63 is an indicator of high family and generic diversity in the collections. Most species were recorded in Nyakarwa Forest and Sorenson similarity matrix showed dissimilarity richness and distribution of mushroom species between sites. The diversity and distribution of species are related to habitat structure variability and species richness decreases from forest to grassland.