Conservation of environmental resources demands monitoring of land use/land cover(LULC) changes. The main objective of this study was to determine the effect of land use/cover change on surface runoff at the Kibungo sub-catchment from 1991 to 2020. Landsat images were used to generate a LULC map of 1991,2008 and 2020 with Kappa values of 86%, 83%, and 84%, respectively, using ENVI 5.2 and Arc GIS 10.4.1. Seven LULC classes were identified: Forest, waterbody/river, the agricultural field, built-up, grassland, bare land, and shrub/bushland. Change detection was done in Land Change Modeler in the TerrSet Geospatial Monitoring and Modeling System. Overall, the area covered by forest, waterbody/rivers, and shrub/bushland were reduced by 40.9, 19.2, and 2.4 km2, respectively, from 1991 to 2020. Increases in the area were observed in agriculture (44.6 km2), built-up area (13.5 km2), grassland area (2.7 km2), and barren land area (17 km2). Built-up and Agricultural field was the leading causes of forest loss (-44.4 km2). The annual surface runoff increased by 94.6 mm/year during that period. There are strong correlations between increased surface run-off depth and built-up (0.99), as well as the Agricultural field (096). This study provides valuable information on LULC change over time at the Kibungo subcatchment for planners, natural resource managers and policymakers.